Quick answer

If you receive a BIR Formal Letter of Demand and Final Assessment Notice (FLD/FAN), you generally have 30 calendar days from receipt to file a valid written administrative protest. Choose either:

Request for reconsideration — asks the BIR to re-evaluate the assessment using records already available; or
Request for reinvestigation — relies on newly discovered or additional evidence, which must be submitted within 60 calendar days from filing the protest.

The protest must identify the assessment, clearly state which findings you dispute, and explain the facts and legal authorities supporting each objection. A vague letter saying only that you disagree may be invalid. Any assessment item you do not properly contest may become final, executory, and demandable.

File with the BIR office authorized to receive the protest—not merely with the Revenue Officer handling the audit—and obtain indisputable proof of timely filing. Section 228 of the National Internal Revenue Code and Revenue Regulations No. 18-2013 govern the principal deadlines.

Critical deadlines

Event or document	Required action	General deadline
Preliminary Assessment Notice (PAN)	Submit a response explaining why the proposed findings are incorrect	15 calendar days from receipt
FLD/FAN	File a written request for reconsideration or reinvestigation	30 calendar days from receipt
Request for reinvestigation	Submit all relevant supporting documents	60 calendar days from filing the protest
Denial by a duly authorized BIR representative	Appeal to the CTA, or elevate the protest to the Commissioner when allowed	30 calendar days from receipt
Denial by the Commissioner	File a Petition for Review with the CTA	30 calendar days from receipt
BIR inaction for 180 days	Either appeal the inaction within the next 30 days or wait for a final BIR decision	See the mutually exclusive options below

These are ordinarily calendar-day periods. The day of receipt is excluded and the final day is included. File early rather than relying on a weekend, holiday, work-suspension, or disaster extension. A special BIR issuance must actually cover your location, office, document, and deadline before you rely on an extension.

There is no minimum peso amount required to use the Section 228 protest procedure.

First identify the document you received

Different BIR documents call for different responses.

Notice of Discrepancy

A Notice of Discrepancy, or NOD, presents issues found during an audit and allows a discrepancy discussion. It is not yet an assessment. Current audit policy requires the NOD to say so and to identify the discrepancies clearly. Use this stage to submit reconciliations and documents before an assessment is issued. See RMO No. 1-2026.

Preliminary Assessment Notice

A PAN states the BIR’s proposed assessment. A response is generally due within 15 days from receipt. Although the formal administrative protest required by Section 228 is directed against the later FLD/FAN, failing to answer the PAN forfeits an important opportunity to correct the findings before they become final assessments.

A PAN is generally required, but Section 228 allows an FLD/FAN to be issued without one when:

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

Outside these exceptions, the absence or improper service of a PAN may be a due-process issue. It should be raised promptly, but it is unsafe simply to ignore the FLD/FAN on the assumption that it is void.

Formal Letter of Demand and Final Assessment Notice

The FLD/FAN is the document that must be administratively protested within 30 days from receipt. It should state the factual and legal bases of the assessment. If it does not, that may affect the assessment’s validity, but a taxpayer should still file a timely protest and expressly raise the defect.

Final Decision on Disputed Assessment

An FDDA is the BIR’s decision on the protest. It should state the facts and legal authorities supporting the decision and identify itself as final. Receipt normally starts another strict 30-day period for the appropriate appeal.

The label is not always conclusive. If a letter, collection notice, or other communication appears to reject the protest finally or directs you to appeal, obtain legal advice immediately rather than waiting for a document titled “FDDA.”

How to prepare and file the protest

1. Fix the receipt date immediately

Record:

The exact date, time, place, and manner of service;
The name, position, and authority of the person who received the notice;
Every page and attachment delivered;
The envelope, registry notice, return card, courier tracking record, or receiving log; and
Any facts showing that service was made at an incorrect address or on an unauthorized person.

The Supreme Court has treated proper service as a fact-sensitive due-process issue. Preserve the evidence instead of assuming the BIR’s stated delivery date is correct.

Create a deadline calendar for the 30-, 60-, 180-, and later 30-day periods. Have a second person verify every calculation.

2. Review the entire audit record

Collect and arrange chronologically:

Letter of Authority or electronic Letter of Authority, including replacements;
Requests for documents and your responses;
Notice of Discrepancy and minutes of discussions;
PAN, your reply, and its supporting documents;
FLD/FAN and assessment schedules;
Tax returns, audited financial statements, and proof of payment;
Ledgers, journals, trial balances, invoices, withholding certificates, contracts, bank records, and reconciliations; and
All emails, letters, transmittals, receiving copies, and meeting notes.

Check both the substance of the assessment and the process used to issue it.

3. Choose the correct form of protest

Request for reconsideration

Choose reconsideration when the assessment can be resolved from records already in the BIR’s possession. It may raise factual or legal questions, but it does not contemplate newly discovered or additional evidence.

The special 60-day documentary-submission period does not apply to a reconsideration. Under RR No. 18-2013, the 180-day period for BIR action is generally counted from filing the protest.

Request for reinvestigation

Choose reinvestigation when you need the BIR to consider newly discovered or additional evidence. Identify in the protest the additional evidence you intend to present.

Submit all relevant supporting documents within 60 days from filing the protest against the FLD/FAN. The Supreme Court confirmed this reckoning point in CIR v. Maxicare Healthcare Corporation. The 60 days do not run from a PAN response.

For a reinvestigation, the BIR’s 180-day action period is generally counted from the submission of the required documents. Use a dated transmittal listing each attachment and stating whether the submission completes the documents supporting the protest.

Select the remedy deliberately. Calling a letter “reconsideration” while promising new evidence creates avoidable uncertainty about the 60-day deadline and the nature of the request.

4. Address every assessment item separately

A valid protest should contain at least:

Taxpayer’s registered name, TIN, address, and contact details;
Date and identifying numbers of the FLD/FAN;
Tax type, taxable period, and amount assessed;
An express statement that the filing is a request for reconsideration or request for reinvestigation;
Every issue and amount being disputed;
Material facts supporting the objection;
Applicable statutes, regulations, and jurisprudence;
For reinvestigation, the additional evidence to be presented;
A clear request for cancellation or adjustment of the identified assessment items; and
The taxpayer’s or properly authorized representative’s signature and authority.

A practical format is an issue-by-issue table:

Assessment item	Amount disputed	Relevant facts	Legal basis	Supporting evidence	Relief requested

Do not rely on a general reservation of rights. Under RR No. 18-2013, an issue may be treated as undisputed when the taxpayer fails to state supporting facts and law. Amounts attributable to undisputed issues may become final and collectible.

5. File with the correct BIR office

Follow the filing instructions in the FLD/FAN. For Regional and Large Taxpayer audit cases covered by RMO No. 6-2023, protest letters and requests for reconsideration or reinvestigation are received by the office of the Revenue Director or ACIR-LTS who signed the PAN/FAN/FLD, then referred for recording and resolution.

Do not assume that handing the protest to the Revenue Officer, sending it to a personal email address, or leaving it with an unrelated RDO section constitutes filing.

Obtain a stamped receiving copy showing:

Date and time received;
Receiving office;
Name or identifying mark of the receiving employee; and
Number of pages or attachments, preferably through a detailed transmittal.

If the office instructs you to use registered mail, courier, email, or another channel, obtain the instruction in writing and preserve proof of dispatch and receipt. Unless an applicable issuance clearly authorizes electronic filing, do not assume an email alone protects the deadline.

If a representative files, include the appropriate written authority—such as a special power of attorney, board authority, or corporate secretary’s certificate—and any identification the receiving office validly requires.

6. Submit reinvestigation documents within 60 days

For a reinvestigation:

Index and paginate the documents;
Connect each document to a specific assessment issue;
Include reconciliations explaining differences between returns, books, financial statements, and third-party data;
Use certified true copies when appropriate while preserving originals;
Obtain a separately stamped transmittal; and
Keep an exact duplicate of everything submitted.

Do not wait for the BIR to identify what evidence you should submit. RR No. 18-2013 defines relevant supporting documents as those necessary to support the taxpayer’s own factual and legal bases.

What happens after the protest

If a duly authorized representative denies it

If the denial is issued by the Commissioner’s duly authorized representative, the taxpayer may generally choose, within 30 days from receipt, to:

File a Petition for Review with the Court of Tax Appeals; or
Elevate the protest to the Commissioner through a request for reconsideration.

An administrative appeal to the Commissioner cannot be a new request for reinvestigation. Only issues addressed in the authorized representative’s decision will be entertained, so the original protest must be complete.

If the Commissioner denies it

A denial by the Commissioner may be appealed to the CTA within 30 days from receipt. A motion asking the Commissioner to reconsider that denial does not suspend or restart the 30-day CTA period under RR No. 18-2013.

The appeal is initiated through a Petition for Review before a CTA Division. It is a formal court proceeding requiring jurisdictional allegations, verification, certification against forum shopping, supporting records, payment of docket fees, and compliance with current filing and electronic-submission rules. The CTA’s official website publishes its current filing notices, while the substantive procedure appears in the Revised Rules of the Court of Tax Appeals.

Engage CTA counsel well before the deadline. Do not treat emailing an electronic copy as a substitute for every requirement applicable to an initiatory pleading.

If the BIR does nothing for 180 days

When the applicable 180-day period expires without action, the taxpayer has two mutually exclusive choices:

Appeal the BIR’s inaction: File with the CTA within 30 days after the 180-day period expires; or
Wait for the final BIR decision: Once that decision is received, appeal it to the CTA within 30 days from receipt.

Choosing one bars the other. The Supreme Court recognized the option to wait in Lascona Land Co., Inc. v. CIR and reaffirmed it in later cases, including Light Rail Transit Authority v. BIR.

Because the correct starting date differs between reconsideration and reinvestigation, have the 180-day computation reviewed before relying on an inaction appeal.

Important current exceptions

A properly consolidated FAN may create a fresh protest period

Under RMO No. 6-2026, certain pending audit cases for the same taxable period may be consolidated at the FAN stage only if strict safeguards are satisfied. These include written taxpayer conformity, proper service, formal supersession of the identified prior FAN, and the absence of finality.

When a qualifying Consolidated FAN is properly issued, a fresh 30-day protest period runs from its receipt. Do not assume that any revised, replacement, or consolidated notice automatically resets the deadline; examine whether it complies with RMO No. 6-2026.

Government work suspensions may produce limited extensions

The BIR has issued special circulars extending listed audit and assessment filings in areas affected by declared government work suspensions. For example, RMC No. 76-2025 covered specified correspondence, offices, locations, and dates affected by severe weather.

Bad weather or an office closure does not justify a self-declared extension. Confirm the exact BIR issuance and its coverage.

Issues worth checking before finalizing the protest

Depending on the documents and facts, review:

Authority and scope

Was the audit supported by a valid LOA or eLA?
Were the assigned Revenue Officers properly authorized?
Did the examination stay within the listed tax types and taxable periods?
Were replacement or consolidated authorities properly issued?

Due process

Was each required notice properly served?
Was a PAN issued unless a statutory exception applied?
Did the PAN and FLD/FAN state the specific factual and legal bases?
Was the taxpayer given the required opportunity to respond and submit evidence?
Did the BIR consider a timely response before issuing the next notice?

Merits and computation

Were sales, purchases, income, withholding taxes, tax credits, or payments double-counted?
Can third-party information be reconciled with the books and returns?
Were exemptions, deductions, zero-rating, tax credits, or treaty positions properly documented?
Were the correct tax period, rates, interest rules, and payment credits used?
Was the assessment issued within the applicable limitation period?

These questions do not automatically invalidate an assessment. Outcomes depend on the notices, audit authority, service records, returns, evidence, and governing law for the particular taxable period.

Evidence to preserve

Keep both physical and secure electronic copies of:

The complete FLD/FAN, PAN, NOD, FDDA, and all envelopes;
Registry receipts, return cards, courier records, email headers, and receiving logs;
LOAs, eLAs, replacement authorities, and written authorizations;
Protest letters, transmittals, stamped receiving copies, and document indexes;
Tax returns, amendments, attachments, financial statements, and payment confirmations;
Books, invoices, withholding certificates, contracts, bank records, and reconciliations;
Minutes, correspondence, and notes of communications with BIR personnel; and
Corporate approvals and authority documents for representatives.

Preserve original electronic files and metadata where receipt, service, or transmission is disputed.

Common mistakes that can make the assessment final

Missing the 30-day FLD/FAN protest deadline;
Treating a PAN response as the required protest against the FLD/FAN;
Filing a generic objection without identifying the protest type, assessment date, facts, and legal bases;
Addressing only the total amount instead of every disputed issue;
Choosing reconsideration when additional evidence is necessary;
Choosing reinvestigation but missing the 60-day document deadline;
Counting the 60 days from the PAN rather than from the FLD/FAN protest;
Filing with the Revenue Officer instead of the authorized receiving office;
Relying on an unacknowledged email or an unstamped copy;
Assuming BIR inaction permits an appeal at any later time;
Filing another request with the Commissioner after the Commissioner’s denial and assuming it stops the CTA deadline; or
Assuming a CTA appeal automatically stops collection.

When professional help is urgent

Consult a Philippine tax lawyer and experienced tax accountant immediately when:

The 30- or 60-day deadline is approaching;
An FDDA or other apparent final denial has been received;
The BIR alleges fraud, falsity, intentional evasion, or non-filing;
The assessment covers multiple years, tax types, or related entities;
Service of the notices is disputed;
A subpoena, criminal referral, warrant of distraint or levy, garnishment, or seizure notice has been issued;
You plan to appeal BIR inaction after 180 days; or
The case must be brought to the CTA.

An appeal to the CTA does not automatically suspend payment or collection. Under Republic Act No. 9282, the CTA may suspend collection when the required grounds are established, but it may require a deposit or surety bond of up to twice the amount claimed.

Frequently asked questions

Must I pay the assessment before protesting?

Generally, Section 228 does not require prior payment before filing an administrative protest. However, amounts attributable to issues you do not validly dispute may become final and demandable. A later CTA appeal also does not automatically suspend collection.

Can I protest only part of the assessment?

Yes, but identify the exact items and amounts disputed. The unprotested portions may become final, executory, and demandable.

Is replying to the PAN enough?

No. A PAN response and an FLD/FAN protest are separate submissions. Even if you replied fully to the PAN, you must timely protest the later FLD/FAN.

What if I never received a PAN?

Raise the issue in the FLD/FAN protest and preserve evidence concerning service. A PAN is normally required unless one of Section 228’s five exceptions applies.

Can I submit supporting documents after 60 days?

For a reinvestigation, failure to submit all relevant documents within 60 days can bar reliance on newly discovered or additional evidence and lead to denial. Do not assume the BIR can extend the statutory period informally.

Is email filing enough?

Not unless an applicable rule or written official instruction authorizes that channel and you can prove timely receipt. Filing with the designated office and securing a stamped receiving copy is the safer course.

What if the BIR remains silent after 180 days?

Either appeal the inaction within the next 30 days or wait for the final BIR decision and appeal that decision within 30 days from receipt. The choices are mutually exclusive.

Does filing a protest stop interest?

Not necessarily. A protest does not by itself eliminate the assessment or statutory additions if liability is ultimately upheld. The correct interest computation depends on the taxable period, notice-and-demand dates, payments, and applicable version of the Tax Code.

Official legal sources

This article provides general legal information, not legal or tax advice for a particular assessment. Deadlines and remedies depend on the actual documents, service history, signatory, taxable period, and procedural posture. Official sources were checked as of August 4, 2026.