Quick answer

If you received a Formal Letter of Demand and Final Assessment Notice (FLD/FAN), file a valid written administrative protest within 30 calendar days from receipt. State whether it is a request for reconsideration or request for reinvestigation, identify every disputed issue, and give the supporting facts and legal grounds. File it with the BIR official or office indicated in the assessment—ordinarily the duly authorized representative who signed the FLD/FAN—and secure proof of timely filing.

For a reinvestigation, submit all relevant supporting documents within 60 days from filing the protest. Missing the 30-day protest deadline, omitting an issue, or failing to submit documents on time can make the assessment or the unprotested portion final, executory, and demandable. These rules apply regardless of the amount assessed; there is no minimum amount before an assessment may be protested.

First identify the document you received

The correct response depends on the document and its procedural stage.

Document or event	What it means	General deadline
Notice of Discrepancy (NOD)	Preliminary audit findings; not yet an assessment	Attend the scheduled discussion and submit supporting documents within the discrepancy-discussion period, which generally may not extend beyond 30 days from receipt
Preliminary Assessment Notice (PAN)	Proposed deficiency assessment	Written response within 15 days from receipt
FLD/FAN	Formal deficiency assessment and demand for payment	Valid administrative protest within 30 days from receipt
Request for reinvestigation filed	Protest relying on additional or newly discovered evidence	All relevant supporting documents within 60 days from filing the protest
FDDA or denial by an authorized BIR representative	Decision on the protest	Within 30 days from receipt, either appeal to the CTA or, when permitted, elevate the matter to the Commissioner
Final denial by the Commissioner	Final administrative decision	Petition for review with the CTA within 30 days from receipt
BIR inaction for 180 days	May permit an appeal based on inaction	Either appeal within 30 days after the 180-day period or await a final decision, subject to the rules below

Treat the date of actual receipt as critical. Preserve the envelope, registry notice, courier tracking, email header if applicable, and a written record of who received the document and when. Service on an authorized tax agent may be treated as service on the taxpayer under Revenue Regulations No. 18-2013.

Respond before the assessment becomes final

1. Use the Notice of Discrepancy stage to correct the record

A Notice of Discrepancy gives the taxpayer an opportunity to explain apparent differences found during the audit. It is not yet a deficiency assessment.

Attend the scheduled Discussion of Discrepancy or promptly request a properly documented rescheduling if genuinely necessary. Present a written reconciliation and documents such as returns, invoices, withholding certificates, contracts, ledgers, bank records, and proof of payment. Under the process introduced by Revenue Regulations No. 22-2020, the discrepancy discussion generally cannot extend beyond 30 days from receipt of the NOD, and necessary supporting documents should be submitted within that period. The BIR’s prescribed NOD format is published in Revenue Memorandum Circular No. 102-2020.

Do not assume that explanations given orally to the revenue officer are part of the record. Put material explanations and submissions in writing and obtain a received copy.

2. Answer the PAN within 15 days

A PAN must ordinarily explain the facts and the law, regulations, or jurisprudence supporting the proposed assessment. File a written response within 15 days from receipt, addressing each tax type, taxable period, computation, and legal issue.

A PAN response is valuable, but it is not a substitute for the formal protest required after an FLD/FAN is issued. BIR procedure treats a PAN response as optional in the sense that the formal Section 228 protest is directed against the FLD/FAN. Failing to answer the PAN, however, allows the BIR to proceed based on its findings.

A PAN is not required in the limited cases listed in Section 228 of the Tax Code:

A mathematical error appears on the face of the return.
There is a discrepancy between tax withheld and the amount actually remitted.
A taxpayer both claimed a refund or tax credit for excess creditable withholding tax and carried over the same amount.
Excise tax on excisable articles was not paid.
An exempt person transferred locally purchased or imported exempt articles to a non-exempt person.

In these situations, the BIR may issue an FLD/FAN directly.

3. File the formal protest within 30 days of receiving the FLD/FAN

This is the deadline that normally determines whether the assessment becomes a disputed assessment. The protest must be more than a request for additional time or a statement that documents are still being collected.

A sound protest should include:

The taxpayer’s registered name, TIN, branch code, address, and contact details.
The assessment number, assessment date, tax type, taxable period, amount, and date received.
A clear statement that the filing is an administrative protest under Section 228.
A clear choice between reconsideration and reinvestigation.
A separate discussion of every issue being disputed.
The material facts, applicable law, regulations, and controlling decisions supporting each objection.
A reconciliation or alternative computation when the dispute concerns amounts.
A list of attachments and the specific proposition each document proves.
A request to cancel or reduce the assessment, stated precisely.
The proper signature and proof of authority of the person signing or filing for the taxpayer.

An issue not disputed or not supported by facts and legal grounds may be treated as undisputed. The corresponding portion of the assessment may then become final and collectible even if other issues were properly protested. These requirements appear in Revenue Regulations No. 18-2013, and the Supreme Court has held that a letter failing to meet them may not create a valid disputed assessment in CIR v. Citysuper, Inc..

Choose the correct kind of protest

Request for reconsideration

Choose reconsideration when the assessment should be re-evaluated using the records already submitted or already in the BIR’s possession. It may raise questions of fact, law, or both, but it does not contemplate additional evidence.

This may be appropriate when, for example:

The BIR misread a return or document already in the docket.
The assessment uses the wrong rate or legal provision.
The computation contains an evident error.
The assessment disregards an existing payment or credit already documented.
The issue is principally legal.

The 60-day period for additional documents does not apply to a request for reconsideration. That does not make an incomplete protest safe: the protest itself must already state the relevant facts and legal grounds.

Request for reinvestigation

Choose reinvestigation when you need the BIR to consider newly discovered or additional evidence. Clearly identify the additional evidence you intend to submit.

All relevant supporting documents must be filed within 60 days from the date the protest was filed. Do not assume the BIR can extend this statutory and regulatory period. BIR procedure provides that evaluation will be based on documents submitted within the period and that later documents may be refused. See Revenue Memorandum Order No. 26-2016.

The filing of one remedy generally precludes the other. A protest is ordinarily treated as a reconsideration unless it clearly states that it is a reinvestigation.

File with the correct BIR office and preserve proof

Responses to the PAN and protests against the FLD/FAN should ordinarily be filed with the duly authorized representative who signed the notice, following the instructions and address stated in the assessment. An administrative appeal from that representative’s adverse decision is filed with the Office of the Commissioner. This filing arrangement is explained in Revenue Memorandum Circular No. 11-2014.

For a paper filing:

Prepare enough identical copies for the BIR and your records.
Bring proof of the signatory’s authority, such as the appropriate special power of attorney, secretary’s certificate, or board authorization.
Have the taxpayer’s copy stamped “Received,” showing the date, receiving office, and receiving personnel.
Check that the stamp appears on the protest and, where practicable, on the attachment list.
Keep the complete filed set in the same order as the BIR submission.

Do not assume that an ordinary email, a message to the revenue officer, or an upload to a system intended for tax-return attachments constitutes a valid protest. If the assessment expressly authorizes electronic, registered-mail, or courier filing, follow every stated requirement and retain the acknowledgment, transmission record, registry receipt, tracking history, and exact files sent. When the permitted filing channel is uncertain, personal filing with a stamped received copy is generally the safer course.

Build the protest around evidence, not conclusions

Preserve and organize:

The Letter of Authority or electronic Letter of Authority and any replacements or amendments.
All document requests, subpoenas, NODs, minutes of discussions, PANs, responses, FLD/FANs, assessment details, FDDAs, collection letters, warrants, and proofs of service.
Filed returns and electronic filing confirmations.
Tax-payment confirmations, bank validations, and BIR Form No. 0605 payments.
Books of account, general and subsidiary ledgers, trial balances, and audit working papers.
Invoices and legacy official receipts relevant to the covered period.
Withholding tax certificates, alphalists, and proof of remittance.
Contracts, purchase orders, delivery documents, billing records, and proof of performance.
Bank statements and reconciliations.
SEC documents, board resolutions, and proof of authority for representatives.
A schedule matching every BIR finding to the taxpayer’s response and supporting exhibit.
Stamped copies and transmission records for every submission.

Keep original electronic data and metadata where possible. Do not alter, recreate, or backdate records. If a document is unavailable, explain why, identify its custodian, and provide reliable alternative evidence.

Review both procedural and substantive defenses

A protest should address the assessment on its merits while preserving legitimate procedural objections. Possible issues include:

The amount was previously paid, credited, or assessed twice.
The BIR used an incorrect tax base, rate, taxable period, or legal provision.
Third-party data was attributed to the wrong taxpayer, branch, or period.
Sales, expenses, withholding credits, exemptions, or zero-rated transactions were incorrectly treated.
The factual assumptions are contradicted by the taxpayer’s books and source documents.
The PAN, FLD/FAN, or FDDA does not adequately state the factual and legal bases.
A required PAN was omitted and no statutory exception applies.
The assessment notice was not properly served.
The audit exceeded the authority, taxpayer, period, or tax types stated in the applicable Letter of Authority.
The assessment was issued after the applicable prescriptive period.

The ordinary period for assessment is generally three years from the last day prescribed for filing the return. If a return was filed late, the period is generally counted from actual filing. Section 222 provides exceptional rules—including a possible 10-year period involving a false or fraudulent return with intent to evade tax or failure to file—and written waivers or special statutory rules may affect the computation. Prescription is highly document- and date-sensitive, so it should be calculated separately for each return, tax type, and taxable period.

A defect in an FDDA may make the decision defective without necessarily erasing every underlying assessment issue. Continue to observe the appeal deadline while raising the defect. Do not wait for the BIR to issue a corrected decision unless the legal effect has been professionally assessed.

Micro and small business taxpayers may also be entitled to reduced civil-penalty and interest rates under the Ease of Paying Taxes Act and Revenue Regulations No. 6-2024. Verify the taxpayer’s official classification and the period covered when checking the BIR’s penalty computation.

What happens after the protest

If an authorized representative denies the protest

Within 30 days from receipt of the FDDA or denial, the taxpayer generally has two mutually exclusive routes:

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

An administrative appeal to the Commissioner does not permit a new reinvestigation. Only the issues properly raised and decided below are ordinarily considered. If the Commissioner later denies the administrative appeal, file the CTA petition within 30 days from receipt.

If the Commissioner denies the protest

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

If the BIR does not act within 180 days

The taxpayer has two choices:

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

These options are mutually exclusive. A taxpayer who files an appeal based on inaction cannot later abandon that route and treat a subsequent BIR decision as creating a new appeal period. The Supreme Court confirmed the option to await a final decision in Lascona Land Co., Inc. v. CIR and applied it to an administrative appeal in Light Rail Transit Authority v. BIR.

Calculate the 180-day period carefully:

For reconsideration, current BIR procedure generally counts from filing of the protest.
For reinvestigation, Section 228 and court decisions refer to the submission of supporting documents, while BIR administrative procedure has counted from the lapse of the 60-day documentation period.

Because those formulations can produce different dates when documents are submitted early, record every submission date and have counsel calculate the earliest defensible CTA deadline.

When appealing an FDDA to the Commissioner or the CTA, Revenue Memorandum Circular No. 43-2023 requires a copy of the appeal to be furnished to the specified BIR assessment official within five days from filing.

Filing with the Court of Tax Appeals

A petition for review involving a disputed BIR assessment is filed with the CTA in Division. The 30-day appeal period is mandatory and jurisdictional; courts generally cannot revive an appeal filed late.

CTA proceedings require compliance with rules on verification, certification against forum shopping, payment of docket fees, service, annexes, paper copies, and electronic copies. Current CTA rules require electronic submission in addition to the prescribed filing of paper copies for initiatory pleadings; email alone should not be assumed sufficient. Check the CTA’s current filing instructions and official email addresses and its latest resolutions and rules immediately before filing.

Tax litigation is document-intensive. Engage a Philippine tax lawyer early enough to prepare the petition, arrange the evidence, and coordinate with the taxpayer’s CPA or finance team.

Does protesting stop collection or require prior payment?

Prior payment of the disputed assessment is generally not required before filing an administrative protest or a CTA appeal.

A timely and valid protest ordinarily prevents the disputed deficiency assessment from becoming final and delinquent while the authorized administrative remedies remain pending. If the BIR nevertheless issues a collection letter, warrant of distraint or levy, garnishment, or similar process, act immediately and preserve proof that the protest and supporting documents were timely filed.

A CTA appeal does not automatically suspend collection. Under Section 11 of the law creating the CTA, the court may suspend collection when it may jeopardize the interests of the government or the taxpayer. The CTA may require a cash deposit or a surety bond of not more than twice the amount claimed, although the necessity or amount of security may be contested in appropriate circumstances. A request for suspension must be properly pleaded and supported with evidence. The current rule is discussed in CIR v. American Wire & Cable Co., Inc..

Interest may continue to affect the amount due if the assessment is ultimately sustained. Payment, partial payment, compromise, or abatement may be considered strategically, but these steps should not be taken without understanding their effect on the disputed issues, any refund remedy, and the pending protest or appeal.

Common mistakes to avoid

Protesting the PAN but failing to protest the later FLD/FAN.
Counting from the date printed on the notice instead of documenting the date received.
Filing only a request for more time or saying that documents will follow.
Failing to identify the protest as reconsideration or reinvestigation.
Using reconsideration while expecting to submit new evidence later.
Missing the 60-day supporting-document deadline for reinvestigation.
Contesting the total amount without addressing each issue separately.
Leaving some tax types or periods unprotested.
Relying on oral discussions or an unstamped courtesy copy.
Filing with the revenue officer instead of the proper signatory or authorized office.
Treating a motion for reconsideration of the Commissioner’s final denial as stopping the CTA deadline.
Assuming BIR inaction automatically creates an unlimited appeal period.
Assuming a CTA appeal automatically stops collection.
Ignoring a collection notice because the taxpayer claims never to have received the FLD/FAN.
Waiting until the last day, when questions about authority, filing venue, office closure, or electronic submission can no longer be corrected.

When legal help is urgent

Obtain immediate tax-litigation advice if:

The 30-day protest or CTA deadline is already running.
An FDDA, final demand, warrant of distraint or levy, garnishment notice, or bank notice has been received.
The BIR claims the assessment is already final.
You learned of the assessment only through a collection notice.
The BIR refuses to receive the protest or disputes its filing date.
Fraud, falsification, undeclared income, or possible criminal liability is alleged.
The assessment involves several years, waivers of prescription, related parties, or multiple Letters of Authority.
Important records are missing or held by a former accountant, employee, customer, or supplier.
The amount could materially threaten payroll, operations, property, or bank accounts.

Frequently asked questions

Can I protest a PAN?

You may and generally should respond within 15 days, but the formal administrative protest contemplated by Section 228 is filed against the FLD/FAN. A PAN response does not eliminate the need for a timely FLD/FAN protest.

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

Do not rely on an extension. These periods are treated as mandatory. Occasionally, the BIR issues official deadline extensions for affected localities during disasters or government suspensions, but only a clearly applicable official issuance should be relied upon.

Must I pay the assessment before protesting?

Generally, no. You may also pay an undisputed portion while protesting the balance. Keep the payment form and proof of payment and identify precisely which portion was settled.

What if the assessment amount is small?

The same protest deadlines apply. There is no monetary threshold below which an FLD/FAN may safely be ignored.

Is an email to the revenue officer enough?

Not unless an applicable BIR issuance or the assessment itself validly authorizes that filing method and all requirements are followed. Use the stated official channel and obtain verifiable proof of receipt.

What if I never received the PAN or FLD/FAN?

Improper service can be a substantial due-process issue, but it is fact-sensitive. Do not ignore a later collection notice. Preserve evidence of the registered address, authorized representatives, mail records, and the first date you learned of the assessment, then seek advice on the correct administrative or CTA remedy.

Can I still submit documents after 60 days?

The BIR may refuse additional documents supporting a reinvestigation after the 60-day period. Submit a complete, indexed set on time. Do not assume that later supplementation will be accepted.

Can I compromise instead of protesting?

The Commissioner has limited statutory authority to compromise or abate taxes on specified grounds, but approval is discretionary and subject to separate requirements. A compromise request does not automatically suspend the protest or appeal deadlines.

Official references

This article provides general Philippine legal information, not legal or tax advice for a particular assessment. The correct remedy may depend on the notices, proof of service, audit authority, tax type, taxable period, documents, and procedural history. Sources and procedures were checked as of 10 August 2026.