Quick answer

To dispute a BIR deficiency tax assessment, file a written administrative protest against the Formal Letter of Demand and Final Assessment Notice (FLD/FAN) within 30 days from receipt. Choose either:

Request for reconsideration — the BIR re-evaluates the assessment using the existing record; or
Request for reinvestigation — you will present newly discovered or additional evidence. All relevant supporting documents must be submitted within 60 days from filing the protest.

A reply to a Preliminary Assessment Notice (PAN) does not replace the required protest against the later FLD/FAN. A late, vague, or incomplete protest can make all or part of the assessment final, executory, and demandable.

Record the exact date and manner of receipt immediately. The 30-day protest period is usually the first deadline that determines whether the assessment can still be contested.

Know which BIR document you received

The correct response depends on the notice:

Document	What it means	Immediate action
Notice of Discrepancy or notice for informal conference	Audit findings are still being discussed	Attend or respond with explanations and records within the period stated
Preliminary Assessment Notice (PAN)	Proposed deficiency assessment	Submit a written response within 15 days from receipt
Formal Letter of Demand and Final Assessment Notice (FLD/FAN)	Formal assessment and demand for payment	File a valid administrative protest within 30 days from receipt
Final Decision on Disputed Assessment (FDDA)	Decision on the protest	Appeal or elevate it, as applicable, within 30 days from receipt
Collection letter, final notice before seizure, warrant of distraint or levy, or garnishment notice	The BIR has begun or is preparing collection	Obtain tax counsel immediately; do not assume an earlier appeal period has been revived

Under Section 228 of the National Internal Revenue Code, a PAN is generally required before an FLD/FAN. The PAN must explain the factual and legal bases of the proposed assessment, and the taxpayer normally has 15 days from receipt to respond.

A PAN is not required when the deficiency results from:

A mathematical error appearing on the face of the return;
A discrepancy between tax withheld and the amount remitted by the withholding agent;
Carry-over of the same excess creditable withholding tax for which a refund or tax credit was also claimed;
Unpaid excise tax on excisable articles; or
A sale, trade, or transfer to a non-exempt person of an article purchased or imported by an exempt person.

In these cases, the BIR may issue the FLD/FAN directly. The absence of a PAN is therefore not automatically a valid objection.

First steps after receiving an FLD/FAN

1. Secure the complete assessment package

Collect the FLD, every assessment notice, schedules of discrepancies, computation sheets, annexes, and the envelope or courier packaging. Check whether pages or attachments referred to in the letter are missing.

Do not rely solely on a scanned copy forwarded by an employee or accountant. Establish when, where, how, and by whom the original was received.

2. Record the receipt details

Preserve:

The actual date and time of delivery;
Registry receipt, return card, courier tracking, or delivery record;
The name and position of the person who accepted it;
The address where it was delivered;
The envelope and all routing stamps; and
Any authority held by the receiving person or tax agent.

Under Revenue Regulations No. 18-2013, BIR notices may be served personally, by substituted service, or by mail. Delivery to a clerk or person in charge at the registered or known business address may constitute substituted service in the circumstances specified by the regulation. Service on an accredited tax agent appointed by the taxpayer is deemed service on the taxpayer.

Refusing delivery is not a safe strategy. The regulations allow documented substituted service. Keep the taxpayer’s BIR registration and address current.

3. Calendar every possible deadline

Treat the day after receipt as the beginning of the working deadline calculation, but have counsel confirm the exact last day, particularly if receipt or service is disputed or the deadline falls on a holiday or non-working day. Work toward an earlier internal deadline.

A request for copies, clarification, conference, or additional time does not by itself suspend the 30-day protest period.

4. Separate each assessment issue

Create a schedule showing:

Tax type and taxable period;
Assessment number;
Basic tax, surcharge, interest, and compromise penalty stated;
BIR’s factual allegation;
BIR’s legal basis;
Taxpayer’s position;
Supporting records; and
Amount disputed or admitted.

This matters because an issue that is not expressly disputed—or for which the protest states no supporting facts and legal basis—may be treated as undisputed. The amount attributable to an undisputed issue becomes final, executory, and demandable.

Choose the correct kind of protest

Request for reconsideration

Choose reconsideration when the case can be resolved from records already available to the BIR. It may involve questions of fact, law, or both, but it does not depend on newly discovered or additional evidence.

The 60-day document-submission period does not apply to a reconsideration. Nevertheless, identify the existing records precisely rather than assuming the reviewing officer will locate them.

Request for reinvestigation

Choose reinvestigation when you need the BIR to consider newly discovered or additional evidence. The protest must identify the evidence you intend to present.

Submit all relevant supporting documents within 60 days from filing the protest. Failure to do so bars the taxpayer from disputing the assessment through newly discovered or additional evidence and results in denial through an FDDA.

When submitting documents in batches, use an indexed transmittal for each batch. On completion, consider filing a written manifestation identifying the complete set and its submission date. This reduces disputes over when the BIR’s 180-day decision period began.

What a valid protest should contain

A protest should be a reasoned challenge, not merely a request for more time or a statement that the taxpayer disagrees. At minimum, include:

Taxpayer identification. State the registered name, TIN, registered address, contact details, taxable period, assessment numbers, and assessed amounts.
Receipt information. Identify the FLD/FAN date and the date and manner of receipt.
Nature of the protest. State expressly whether it is a request for reconsideration or reinvestigation. For reinvestigation, specify the newly discovered or additional evidence to be submitted.
Scope. State whether the entire assessment or only identified portions are disputed.
Issue-by-issue facts. Answer each discrepancy separately and cite the supporting annexes.
Legal grounds. State the applicable statutes, regulations, and controlling jurisprudence supporting each objection.
Correct computation. Where possible, provide a reconciliation or alternative calculation rather than only denying the BIR’s figures.
Requested relief. Ask for cancellation or reduction of the identified assessments and the issuance of the appropriate decision.
Annex index. Number and describe every attachment, including the number of pages.
Authority and signature. Have the taxpayer or properly authorized representative sign and attach the relevant authority, such as a secretary’s certificate, board resolution, or special power of attorney when applicable.

The Supreme Court has emphasized that compliance with the prescribed protest requirements is necessary before there is a disputed assessment that the CTA can review. A letter that does not identify the nature of the protest and its legal grounds may be ineffective. See Commissioner of Internal Revenue v. V.Y. Domingo Jewellers, Inc..

Where and how to file

Under Revenue Memorandum Circular No. 11-2014, the response to the PAN and the protest against the FLD/FAN should be filed with the duly authorized representative of the Commissioner who signed the notice. An administrative appeal from the adverse decision or inaction of that representative is filed with the Office of the Commissioner.

Before filing:

Confirm the correct receiving office using the notice and current BIR instructions;
Prepare enough copies for the BIR and the taxpayer;
Obtain a duplicate bearing the official received stamp, date, receiving office, and receiving personnel’s identification;
Ensure the received copy covers the letter and annex inventory; and
Retain mailing, courier, electronic, or other transmission proof if the particular office has expressly authorized that method.

Do not assume that sending the protest to the audit examiner, an unofficial email address, or the taxpayer’s ordinary RDO is sufficient. The cited regulations do not establish ordinary email as a universal filing channel for assessment protests. If the BIR gives special filing instructions, obtain them in writing and preserve proof of compliance.

Review the validity and merits of the assessment

Potential grounds depend on the actual notices, audit authority, returns, records, and taxable periods. Review at least the following.

Was the audit properly authorized?

Check the Letter of Authority or electronic Letter of Authority, the officers named, taxable period, tax types, issuing authority, and any reassignment or replacement authority.

The Supreme Court has held that an examination by a substitute revenue officer without the required separate or amended authority can invalidate the assessment. See Commissioner of Internal Revenue v. McDonald’s Philippines Realty Corporation. The BIR’s current audit framework is found in RMO No. 1-2026, subject to its subsequent clarifications.

Was the assessment issued on time?

The ordinary assessment period is generally three years under Section 203 of the Tax Code, subject to exceptions, valid written waivers, special statutes, and the rules for false or fraudulent returns or failure to file a return. The correct starting date and any suspension or extension are document-specific.

Preserve the original returns, electronic filing confirmations, payment records, waivers, acceptance documents, and audit correspondence. Do not sign or concede the validity of a waiver without reviewing its dates, authority, and terms.

Did the BIR follow due process?

The FLD/FAN must inform the taxpayer in writing of the facts and law, rules, regulations, or jurisprudence on which the assessment is based. A bare computation or general statutory citation may be inadequate if it does not explain how the law applies to the asserted facts. The assessment must also make a definite demand for payment, including the amount and due date.

Relevant decisions include Commissioner of Internal Revenue v. Fitness by Design, Inc. and Commissioner of Internal Revenue v. Arturo E. Villanueva, Jr..

Due-process objections should be raised in the timely protest. Do not simply ignore an assessment because you believe it is void.

Is the computation factually and legally correct?

Reconcile the assessment against:

Filed returns and amendments;
Proof of tax payments;
Books, ledgers, and trial balances;
Audited financial statements;
Sales invoices and official records applicable to the period;
Withholding tax certificates and alphalists;
Contracts, billing statements, and delivery records;
Importation or export documents;
Bank and third-party information used by the BIR; and
Applicable tax rates, exemptions, deductions, credits, and transitional rules for the particular period.

A procedural objection should not replace a substantive defense. Present both when supported by the records.

What happens after filing

BIR action within 180 days

For a request for reconsideration pending before the Commissioner’s duly authorized representative, the 180-day period is counted from filing of the protest. For a request for reinvestigation, it is counted from submission of the required supporting documents within the 60-day period.

The regulation contains separate language for protests and administrative appeals before the Commissioner. Because the correct starting point can depend on the route taken and the filing history, keep a dated procedural chronology and obtain advice before calculating an inaction appeal.

If an authorized representative denies the protest

Within 30 days from receipt, the taxpayer may either:

File a petition for review with the CTA Division; or
Elevate the matter to the Commissioner through a request for reconsideration.

No reinvestigation is allowed at this administrative-appeal stage, and only the issues raised in the authorized representative’s decision will be entertained by the Commissioner.

If the Commissioner denies the protest or administrative appeal

File a petition for review with the CTA Division within 30 days from receipt. A motion for reconsideration addressed to the Commissioner does not suspend or restart this 30-day CTA period.

If the BIR does not act within 180 days

The taxpayer has two mutually exclusive options:

Appeal the inaction to the CTA within 30 days after the 180-day period expires; or
Await the BIR’s final decision and appeal that decision within 30 days from receipt.

The Supreme Court confirmed these alternatives in Lascona Land Co., Inc. v. Commissioner of Internal Revenue and Light Rail Transit Authority v. Bureau of Internal Revenue. Once one remedy is chosen, the taxpayer cannot shift to the other.

Appealing to the Court of Tax Appeals

A CTA case is commenced by a petition for review in the proper CTA Division. Under the Revised Rules of the Court of Tax Appeals, the petition must establish jurisdiction, state the complete material facts and issues, be verified, contain the required certification against forum shopping, attach the challenged decision, and be accompanied by proof of payment of docket fees.

A proper motion filed before the original appeal period expires, with the required fees, may obtain an additional period of no more than 15 days to file the petition. An extension is not automatic and should never be treated as a substitute for timely preparation.

An appeal does not automatically stop BIR collection. If collection may jeopardize the taxpayer’s or the Government’s interests, the taxpayer may ask the CTA to suspend collection. The court may require a cash deposit or an acceptable surety bond of up to twice the disputed amount, subject to the governing law and recognized exceptions. The motion must be supported by evidence, not merely an allegation of hardship.

Evidence to preserve

Keep both paper and secure electronic copies of:

The eLA or LOA and every replacement, amendment, or assignment document;
Notices of discrepancy, minutes of audit meetings, PAN, FLD/FAN, FDDA, and collection notices;
Envelopes, registry records, courier tracking, return cards, and receiving logs;
Every response, protest, appeal, transmittal, and stamped received copy;
Returns, filing confirmations, payment receipts, and withholding certificates;
Books, invoices, contracts, bank records, and reconciliation schedules;
Communications with revenue officers and BIR offices;
Corporate authorizations and tax-agent appointment documents; and
A master chronology of all issuances, receipts, submissions, and deadlines.

Preserve original documents. CTA proceedings may require authentication, comparison with originals, and formal presentation of evidence.

Common mistakes

Treating a PAN response as the protest against the FLD/FAN;
Waiting for a conference or requested documents while the 30-day period runs;
Filing with the examiner instead of the proper signatory or receiving office;
Failing to state whether reconsideration or reinvestigation is requested;
Using a blanket denial without facts and legal grounds for every issue;
Omitting an assessment item and unintentionally allowing it to become final;
Choosing reinvestigation but missing the 60-day document deadline;
Failing to preserve proof of receipt and filing;
Assuming BIR silence after 180 days automatically ends the case;
Filing a motion for reconsideration with the Commissioner and assuming it stops the CTA deadline;
Waiting for a warrant, garnishment, or seizure notice before seeking court relief; and
Assuming a CTA appeal automatically suspends collection.

When legal help is urgent

Consult a Philippine tax lawyer promptly if:

The 30-day protest or appeal deadline is already running;
Receipt or service is disputed;
The assessment involves several tax types, taxable years, or large amounts;
Fraud, falsity, a 50% surcharge, criminal referral, or tax-evasion allegations appear;
The audit may have been conducted without a valid eLA or LOA;
Prescription or the validity of a waiver is involved;
Required evidence cannot be assembled within 60 days;
You received an FDDA or another letter that appears to finally deny the protest;
The BIR issued a collection letter, garnishment, warrant of distraint or levy, or notice of sale; or
CTA proceedings or suspension of collection may be necessary.

Frequently asked questions

Can I protest a PAN?

You may and

Quick answer

To contest a BIR deficiency tax assessment, file a valid written protest against the Formal Letter of Demand and Final Assessment Notice (FLD/FAN) within 30 days from receipt. Choose either:

Reconsideration — re-evaluation using the existing BIR record; or
Reinvestigation — re-evaluation using newly discovered or additional evidence. All supporting documents must be submitted within 60 days from filing the protest.

Address every disputed issue separately and state the supporting facts and legal grounds. An unsupported or omitted issue may be treated as undisputed and become final, executory and demandable.

If the protest is denied, the next deadline is generally 30 days from receipt of the adverse decision. Depending on who issued that decision, the remedy may be an administrative appeal to the Commissioner of Internal Revenue or a petition for review with the Court of Tax Appeals (CTA). These deadlines are strict under Section 228 of the National Internal Revenue Code and Revenue Regulations No. 18-2013.

First identify what you received

Not every BIR communication is the assessment that starts the 30-day protest period.

Document	What it means	Immediate response
Letter of Authority or electronic LOA	Authorizes identified revenue officers to conduct an audit within its stated scope	Verify the officers, taxable period and tax types; preserve the original
Notice of Discrepancy or informal-conference notice	Gives the taxpayer an opportunity to discuss audit findings before assessment	Reconcile the findings and submit explanations and records promptly
Preliminary Assessment Notice (PAN)	States the BIR’s proposed assessment	File a detailed response within 15 days from receipt
FLD/FAN	The formal assessment and demand for payment	File the formal administrative protest within 30 days from receipt
Final Decision on Disputed Assessment (FDDA)	Decides the protest in whole or in part	Determine the correct appeal immediately; the usual period is 30 days from receipt
Collection letter, final notice before seizure, warrant of distraint or levy, or garnishment	Signals collection activity	Obtain urgent tax-law advice; do not assume it creates a new protest or appeal period

A response to a PAN does not replace the required protest against a later FLD/FAN. Conversely, waiting for an FDDA without first filing a valid FLD/FAN protest can allow the assessment to become final. The Supreme Court has repeatedly required taxpayers to exhaust the prescribed administrative remedy, including in Commissioner of Internal Revenue v. V.Y. Domingo Jewellers, Inc..

Respond to the PAN even though it is not yet the final assessment

A taxpayer generally has 15 days from receipt of the PAN to respond. Use that opportunity to correct factual errors, present reconciliations and identify legal objections before the BIR issues the FLD/FAN.

A PAN must generally precede the formal assessment. Section 228 permits the BIR to issue an FLD/FAN without a PAN only when:

The deficiency results from a mathematical error appearing on the face of the return;
There is a discrepancy between tax withheld and tax actually remitted by the withholding agent;
A taxpayer both claimed a refund or tax credit for excess creditable withholding tax and carried over the same amount to the succeeding taxable year;
Excise tax on excisable articles was not paid; or
An article acquired tax-free by an exempt person was sold, traded or transferred to a non-exempt person.

Outside these exceptions, failure to provide the required PAN and opportunity to respond may be a due-process ground against the assessment. Do not simply ignore an allegedly defective assessment, however. Raise the defect expressly in a timely protest.

Record the date and manner of receipt

The receipt date controls several deadlines. Immediately preserve:

The complete notice, demand letter, assessment forms and every annex;
The envelope, registry notice, courier pouch and tracking information;
The date, time and place of delivery;
The identity and position of the person who received it; and
Any email or message concerning delivery.

Under RR No. 18-2013, BIR assessment notices may be served personally, by substituted service, registered mail, professional courier or, where those services are unavailable, ordinary mail. A notice may in appropriate circumstances be left with a clerk or person in charge at the registered business address. Service on an accredited tax agent appointed under the applicable regulations is deemed service on the taxpayer.

Refusing a notice or failing to update the registered address is therefore unsafe. If receipt or service is disputed, calculate the deadline conservatively from the earliest plausible receipt date while expressly preserving the service objection. The Supreme Court has held that when receipt is genuinely denied, the BIR must prove proper service with competent evidence; see Commissioner of Internal Revenue v. Villanueva.

Choose the correct type of protest

Request for reconsideration

Choose reconsideration when the protest asks the BIR to re-evaluate the assessment using the existing record, without newly discovered or additional evidence. It may raise factual questions, legal questions or both.

The 60-day document-submission period does not apply to reconsideration. That does not make a bare objection sufficient: the protest must still state the facts and legal authorities supporting every contested issue.

Request for reinvestigation

Choose reinvestigation when the protest depends on newly discovered or additional evidence that the taxpayer intends to present.

Identify that evidence in the protest and submit all relevant supporting documents within 60 days from filing the protest. Failure to meet that period bars the taxpayer from challenging the assessment through the additional evidence and results in denial of the reinvestigation under RR No. 18-2013.

When submitting documents in batches, keep an exact inventory and consider filing a written manifestation identifying the date on which the submission became complete. That date can affect the 180-day period for BIR action.

What a valid protest should contain

There is no substitute for an issue-specific protest. At minimum, the letter should:

Identify the taxpayer by registered name, TIN and registered address;
Identify the FLD/FAN, assessment numbers, taxable period, tax types and amounts;
State the date and manner in which the FLD/FAN was received;
Expressly state whether the protest is a request for reconsideration or a request for reinvestigation;
If requesting reinvestigation, identify the newly discovered or additional evidence to be submitted;
State whether the entire assessment or only specified portions are disputed;
Address each assessment item separately;
For every issue, state the material facts, computation and applicable statutes, regulations or jurisprudence;
Identify and attach the supporting evidence, with a numbered annex list;
Request the specific relief sought, such as cancellation or reduction of particular assessment items; and
Be signed by the taxpayer or a properly authorized representative, with the necessary proof of authority.

A vague letter asking the BIR to “reconsider,” requesting copies of records, or stating only that the assessment is excessive may not be a valid protest. In China State Philippines Construction Corporation v. Commissioner of Internal Revenue, the Supreme Court emphasized that a purported protest that does not comply with RR No. 18-2013 does not create a disputed assessment that the CTA can review.

If the FLD/FAN contains several issues, contest each intended issue with its own facts and legal grounds. Under RR No. 18-2013:

An issue not protested becomes final, executory and demandable; and
An issue nominally disputed but unsupported by facts and applicable law may likewise be treated as undisputed.

The BIR may collect the tax, surcharge and interest attributable to those undisputed portions.

Where and how to file

Under Revenue Memorandum Circular No. 11-2014, the protest should be filed with the office of the Commissioner’s duly authorized representative who signed the FLD/FAN. An administrative appeal from that representative’s adverse decision is filed with the Office of the Commissioner.

Before the deadline:

Confirm the correct receiving office using the FLD/FAN and written BIR instructions;
File enough copies for the office to retain one and stamp the taxpayer’s complete duplicate;
Obtain a received copy showing the date, receiving office and receiving personnel;
Have the receiving copy acknowledge the annex list or total number of attachments;
Preserve any registry receipt, return card, courier proof or official electronic acknowledgment; and
Do not rely on an ordinary email unless a current BIR issuance or specific written instruction expressly authorizes that channel for the filing.

If the receiving office refuses the filing or directs it elsewhere, document what happened and obtain professional assistance before the period expires.

Review both the substance and the validity of the assessment

The protest should address the actual tax computation, but procedural defects may also matter. Review, among other things:

Whether the audit was conducted by revenue officers properly named and authorized in a valid LOA or replacement eLA;
Whether the officers stayed within the authorized taxable period and scope;
Whether a PAN was properly issued when required;
Whether the notices were validly served;
Whether the FLD/FAN clearly explains the material facts and applicable law for every assessment item;
Whether it states a definite amount and due date rather than a tentative liability;
Whether the assessment was issued within the applicable prescriptive period;
Whether any waiver extending the assessment period exists and is valid;
Whether payments, withholding credits, carryovers and prior adjustments were correctly recognized; and
Whether the BIR considered the taxpayer’s explanations and evidence.

An assessment must allow an intelligent protest; merely listing amounts or citing statutory provisions without connecting them to the material facts may be insufficient. The requirement protects substantive due process, as discussed in Commissioner of Internal Revenue v. Fitness by Design, Inc..

Authority to audit is also material. The Supreme Court has held that substituting revenue officers without the required new or amended LOA can invalidate the resulting assessment; see Commissioner of Internal Revenue v. McDonald’s Philippines Realty Corporation. Application of that rule remains dependent on the particular authorization documents and the current BIR audit framework, including RMO No. 1-2026 and related issuances.

Track the 180-day period

For a protest handled by the Commissioner’s duly authorized representative, RR No. 18-2013 generally counts the BIR’s 180-day action period:

From the filing of the protest for a request for reconsideration; or
From the submission of the required documents, made within the 60-day period, for a request for reinvestigation.

The regulation separately addresses protests and administrative appeals pending with the Commissioner. Because the correct starting date can depend on the route taken and the filing record, document every date and obtain a case-specific calculation if the 180-day period may be used for a CTA appeal.

What to do after an adverse BIR decision

Decision by a duly authorized representative

Within 30 days from receipt, the taxpayer may generally choose either to:

File a petition for review with the CTA; or
Elevate the matter to the Commissioner through a request for reconsideration.

An administrative appeal to the Commissioner cannot be a reinvestigation. Only the issues addressed in the authorized representative’s decision will be entertained under RR No. 18-2013.

Decision by the Commissioner

File a petition for review with the CTA within 30 days from receipt. A motion asking the Commissioner to reconsider the denial does not suspend or restart the 30-day CTA period.

Do not assume that a collection notice supplies a fresh appeal period. The controlling question is whether an earlier communication already constituted the final, adverse decision on the protest. Seek urgent advice whenever a document denies the protest, calls itself final or unconditionally demands payment.

Options when the BIR does not act within 180 days

After the applicable 180-day period expires without a decision, the taxpayer generally has two mutually exclusive options:

Appeal the inaction by filing a petition for review with the CTA within the next 30 days; or
Wait for the final BIR decision, then appeal that decision within 30 days from receipt.

The Supreme Court confirmed the option to wait in Lascona Land Co., Inc. v. Commissioner of Internal Revenue and Light Rail Transit Authority v. Bureau of Internal Revenue. Once the taxpayer elects and pursues one route, it cannot switch to the other. A late petition purporting to appeal the BIR’s inaction can therefore be fatal.

Appealing to the Court of Tax Appeals

The petition for review is filed with a CTA Division. Under the Revised Rules of the Court of Tax Appeals, it must include allegations establishing jurisdiction, the complete material facts, issues and reasons for review. It must be verified, contain a certification against forum shopping, attach the required decision and be accompanied by payment of docket and lawful fees.

A proper motion filed—and the required fees paid—before the original period expires may allow an additional period of not more than 15 days to file the petition. The extension is discretionary, not automatic, and should never be treated as a substitute for preparing within the original 30 days.

An administrative or judicial appeal does not automatically stop tax collection. The CTA may suspend collection when it finds that collection may jeopardize the interests of the Government or the taxpayer. It may require a cash deposit or an acceptable surety bond of up to twice the disputed amount, subject to the governing statute, rules and jurisprudential exceptions. A motion to suspend collection requires evidence and should be prepared urgently if distraint, levy, garnishment or sale is threatened.

Evidence to preserve

Maintain a single chronological assessment file containing:

LOA or eLA, replacement authority and proof of service;
Requests for records, summonses, notices of discrepancy and conference minutes;
PAN, PAN response and proof of filing;
FLD/FAN, schedules, annexes, envelopes and delivery records;
Protest letter, annex inventory and proof of timely receipt by the BIR;
Every supporting-document submission and acknowledgment;
FDDA and subsequent collection communications;
Tax returns, filing confirmations and proof of payment;
Books, ledgers, journals and trial balances;
Audited financial statements and tax reconciliations;
Invoices, receipts, withholding certificates and creditable-tax schedules;
Contracts, bank records, payroll data and transaction correspondence; and
Corporate authorizations, secretary’s certificates, powers of attorney and tax-agent documents.

Keep original records intact. Work from indexed copies and preserve electronic files in their native format where possible.

Common mistakes

Treating a PAN response as the protest against the FLD/FAN;
Counting from the notice date instead of the date of receipt—or failing to preserve receipt evidence;
Filing a generic disagreement without facts and legal grounds for each issue;
Choosing reconsideration while depending on evidence not already in the record;
Choosing reinvestigation but missing the 60-day document deadline;
Omitting one assessment item and unintentionally allowing it to become final;
Filing with the wrong BIR office without obtaining timely receipt from the proper office;
Waiting for a collection notice after an FDDA has already started the CTA period;
Filing another motion with the Commissioner and assuming it pauses the CTA deadline;
Appealing BIR inaction after the special 30-day window has expired; and
Assuming a CTA appeal automatically stops collection.

When professional help is urgent

Consult a Philippine tax lawyer promptly if:

The 30-day or 60-day period has begun or may expire soon;
The amount, taxable periods or number of disputed issues is substantial;
The assessment alleges fraud, intentional evasion or substantial underdeclaration;
The BIR invokes a 10-year assessment period or relies on a waiver of prescription;
Receipt, service, the signatory’s authority or the auditors’ LOA is disputed;
You received an FDDA, warrant of distraint or levy, garnishment notice or notice of sale;
The BIR has contacted banks, customers, debtors or government payors concerning collection;
Records are missing or cannot be assembled within 60 days; or
You intend to appeal to the CTA or request suspension of collection.

Frequently asked questions

Can I protest the PAN?

You should respond to it within 15 days, but the PAN is ordinarily a proposed assessment. If the BIR later issues an FLD/FAN, file a separate formal protest within 30 days from receipt.

Must I pay the disputed assessment before protesting?

Section 228 does not generally make prior payment a condition for an administrative protest or CTA appeal. Undisputed assessment items can nevertheless become immediately final and demandable, and an appeal does not automatically suspend collection.

Can the BIR extend the 30-day protest or 60-day document periods?

The governing rules do not provide a general discretionary extension of those periods. Treat them as firm. The separate CTA rule allowing a limited extension for filing a petition does not extend the BIR protest deadline.

What if the FLD/FAN lacks factual explanations?

Raise that defect expressly and timely. Section 228 requires the taxpayer to be informed in writing of the facts and law supporting the assessment. Whether a particular notice substantially complies depends on its full contents and related written communications.

What if the assessment was sent to an old address?

Do not assume the assessment is ineffective. Examine the BIR registration record, the manner of service, who received it and whether the BIR knew another address. Preserve the delivery evidence and protest within the earliest defensible deadline while reserving the service objection.

Does silence after 180 days mean I automatically win?

No. It gives the taxpayer the option to appeal the inaction within the prescribed 30-day window or to await a final BIR decision. The underlying assessment is not automatically cancelled.

Can I wait for a warrant before going to the CTA?

Usually not. A warrant or collection letter generally does not revive an expired appeal from an earlier final decision. Act when the protest is denied or when the applicable 180-day period creates the option to appeal inaction.

Key official materials

This article provides general legal information, not legal or tax advice for a particular assessment. Applicable remedies can depend on the notices, authority documents, evidence and exact dates in the taxpayer’s file. Sources and procedures were checked as of 3 August 2026.