How to Protest a BIR Tax Assessment

Quick answer

If you receive a BIR Formal Letter of Demand and Final Assessment Notice (FLD/FAN) and disagree with it, the safest course is to file a written administrative protest within 30 days from your actual receipt of the FLD/FAN. The protest must be either a request for reconsideration or a request for reinvestigation, must identify the assessment being challenged, and must state the factual and legal grounds for disputing the assessment. A vague objection or a late protest can cause the assessment to become final, executory, and demandable.

If you choose reinvestigation because you intend to submit newly discovered or additional evidence, all relevant supporting documents must generally be submitted within 60 days from filing the protest. That 60-day document-submission period does not apply in the same way to a request for reconsideration, which asks the BIR to re-evaluate the assessment on the existing record.

Do not confuse the FLD/FAN with an earlier Notice of Discrepancy (NOD) or Preliminary Assessment Notice (PAN). A NOD is not yet an assessment. A PAN is normally a proposed assessment and generally gives the taxpayer 15 days from receipt to respond. The FLD/FAN is the document that ordinarily triggers the 30-day period for the formal administrative protest under Section 228 of the National Internal Revenue Code (NIRC). (Bir Cdn)

The basic timetable is:

Stage What normally happens Important period
Notice of Discrepancy Audit discrepancies are discussed; it is not yet an assessment Discussion generally cannot extend beyond 30 days from receipt
Preliminary Assessment Notice Proposed deficiency assessment Respond within 15 days from receipt
FLD/FAN Final assessment and demand Protest within 30 days from receipt
Reinvestigation Additional/new evidence will be submitted Supporting documents within 60 days from protest
BIR action on reconsideration BIR considers protest based on existing record 180 days counted from filing of protest
BIR action on reinvestigation BIR considers protest and supporting evidence 180 days generally counted from submission of required documents
Adverse FDDA or CIR decision Taxpayer may have CTA remedy Usually 30 days from receipt
BIR inaction after applicable 180 days Taxpayer may appeal based on inaction or wait for a final decision If appealing on inaction, generally within 30 days after the 180-day period

These periods can determine whether a tax liability becomes enforceable, so calculate them from documentary proof of receipt rather than simply from the date printed on the BIR notice.

There is an important but narrow qualification. In Ortiz Memorial Chapel, Inc. v. Commissioner of Internal Revenue, decided on December 3, 2025, the Supreme Court reiterated that although the general rule makes an unprotested assessment final, an assessment that is void ab initio for a defect going to its validity—such as a fundamental denial of the due-process requirement to state its factual and legal bases—cannot acquire validity merely because the taxpayer failed to protest on time. That is an exception, not a deadline strategy. A taxpayer who still has time should file a proper protest rather than rely on later litigation over whether an assessment was void from the beginning. (E-Library)

Understand which BIR document you received

The first step is to identify the document correctly. Different notices trigger different rights and deadlines.

Notice of Discrepancy

Under the current audit framework, the BIR may issue a Notice of Discrepancy after an audit identifies possible deficiencies. The purpose is to give the taxpayer an opportunity to explain the discrepancies and submit documents during the Discussion of Discrepancy. Current BIR guidance expressly states that the NOD is not yet an assessment. (Bir Cdn)

The Discussion of Discrepancy generally cannot extend beyond 30 days from receipt of the NOD. BIR Revenue Memorandum Order No. 1-2026 also directs revenue officers to clearly identify the discrepancies and to anchor later assessment notices on issues that remain unresolved after this stage. (KPMG Assets)

Use this stage seriously. Producing contracts, reconciliations, invoices, withholding certificates, accounting schedules, bank records, tax returns, and explanations early may prevent an issue from becoming a formal assessment.

Preliminary Assessment Notice

If the issue remains unresolved and the BIR determines that there is sufficient basis for a deficiency assessment, it will ordinarily issue a PAN stating in detail the facts and the law, rules, regulations, or jurisprudence supporting the proposed assessment. The taxpayer normally has 15 days from receipt to respond.

A PAN is generally required, but Section 228 recognizes specific exceptions. A PAN is not required where the deficiency results from:

  • a mathematical error appearing on the face of the return;
  • a discrepancy between tax withheld and the amount actually remitted by a withholding agent;
  • specified circumstances involving a refund or tax-credit claim that was also carried over and applied against succeeding liabilities;
  • unpaid excise tax on excisable articles; or
  • the sale, transfer, or disposition to a non-exempt person of specified articles originally acquired by an exempt person.

In those statutory situations, the BIR may issue the FLD/FAN without first issuing a PAN.

Formal Letter of Demand and Final Assessment Notice

The FLD/FAN is the crucial document for purposes of an administrative protest. It demands payment of the deficiency tax and must inform the taxpayer of the factual and legal bases for the assessment. Section 228 expressly provides that taxpayers must be informed in writing of the law and facts on which an assessment is made; otherwise, the assessment is void.

Once an FLD/FAN is received, do not assume that an earlier response to the NOD or PAN is enough. A separate, valid protest against the FLD/FAN should be filed within the 30-day period.

Step 1: Establish the exact date you received the FLD/FAN

The 30-day period runs from receipt of the assessment, not simply from the date appearing on the BIR document. Preserve whatever proves when and how it was received.

Keep:

  • the original envelope;
  • registry notices and postal records;
  • courier waybills and delivery records;
  • the FLD/FAN and all attachments;
  • an email with complete headers if an assessment was electronically served;
  • the name and position of the person who received it;
  • any acknowledgment or receiving copy; and
  • internal company records showing when the document reached the responsible officer.

Disputes over service and receipt can become decisive. However, taxpayers should not assume that every technical defect in service automatically invalidates an assessment. The Supreme Court has recognized substantial compliance in circumstances where the taxpayer actually received the notices and had a meaningful opportunity to protest. The effect of a service defect therefore depends on the facts. (E-Library)

Step 2: Choose between reconsideration and reinvestigation

A protest must identify whether it is a request for reconsideration or a request for reinvestigation.

Request for reconsideration

Choose reconsideration when you are asking the BIR to re-evaluate the assessment using evidence and records already available before issuance of the FLD/FAN, without intending to present newly discovered or additional evidence.

Examples may include arguments that:

  • the examiner misapplied a provision of the Tax Code;
  • the BIR's own computation contains an error;
  • an already-submitted invoice, return, contract, or schedule was misunderstood;
  • an expense was disallowed despite evidence already in the audit docket; or
  • the BIR used an incorrect legal characterization of an existing transaction.

The special 60-day supporting-document deadline applicable to reinvestigation does not apply to reconsideration in the same manner. The 180-day period for BIR action on a reconsideration is generally counted from the filing of the protest.

Request for reinvestigation

Choose reinvestigation when the protest depends on newly discovered or additional evidence that you intend to submit.

The protest should identify the evidence you intend to present. All relevant supporting documents must then be submitted within 60 days from filing the protest. Failure to comply can cause serious consequences for the assessment and the taxpayer's ability to dispute it through additional evidence.

The 180-day period for action on a reinvestigation is generally reckoned from submission of the required supporting documents within the prescribed period.

The BIR treats reconsideration and reinvestigation as alternative remedies at this stage, so determine before filing which remedy fits the evidence you actually need. (Bir Cdn)

Step 3: Make the protest specific enough to be valid

A one-paragraph letter saying simply, “We disagree with the assessment,” is dangerous.

Under RR No. 18-2013 and BIR guidance, the written protest should identify at least:

  1. the date of the assessment notice;
  2. whether the protest is a request for reconsideration or reinvestigation;
  3. if reinvestigation is chosen, the newly discovered or additional evidence intended to be submitted; and
  4. the applicable law, regulations, rules, or jurisprudence supporting the protest.

For each disputed item, the protest should also explain the relevant facts and why the BIR's finding is wrong.

For example, instead of writing:

“We dispute the deficiency income tax.”

a useful protest should identify the particular adjustment—such as alleged undeclared income or a disallowed expense—state what actually occurred, cite the records supporting the taxpayer's position, address the BIR's factual assumptions, and explain the applicable legal rule.

This matters especially when an FLD/FAN contains several tax types or adjustments. RR No. 18-2013 provides that an issue which the taxpayer does not dispute may become final, executory, and demandable. The same danger exists when a purported protest fails to state the factual and legal grounds supporting the challenge to a particular issue.

Step 4: File the protest with the correct BIR office

BIR guidance directs that a protest against an FLD/FAN be addressed to the appropriate Assistant Commissioner, Regional Director, or authorized higher revenue official and filed with the office that issued the FLD/FAN.

RMC No. 15-2020's prescribed procedures recognize filing:

  • in person; or
  • through registered mail.

For registered mail, the post-office stamp on the envelope is treated as the filing date under that guidance, and the envelope becomes part of the case docket.

For personal filing, obtain a clearly dated BIR-stamped receiving copy.

Do not casually assume that sending a protest to a revenue officer's ordinary email address is equivalent to filing the statutory protest. Temporary electronic procedures have existed for particular circumstances, but ordinary assessment protests should be filed through a channel authorized by the governing BIR rules or a current specific issuance.

Step 5: Separate disputed and undisputed amounts

If you contest only some issues in the FLD/FAN, the amounts attributable to the undisputed issues may become final, executory, and demandable. BIR regulations contemplate payment of those uncontested portions while the taxpayer continues to protest the remaining assessment.

Accordingly, review each tax type separately:

  • income tax;
  • VAT or percentage tax;
  • expanded withholding tax;
  • withholding tax on compensation;
  • final withholding tax;
  • documentary stamp tax;
  • excise tax; and
  • penalties or other items included in the assessment.

Do not inadvertently leave an item uncontested merely because the protest focuses most of its discussion on a larger issue.

Step 6: Submit all reinvestigation evidence within 60 days

For a request for reinvestigation, prepare the evidentiary record immediately.

Relevant documents may include:

  • filed tax returns and amendments;
  • audited financial statements;
  • general ledgers and subsidiary ledgers;
  • trial balances;
  • invoices and supporting documents;
  • withholding tax certificates;
  • contracts and purchase orders;
  • bank statements and reconciliation schedules;
  • proof of tax payments;
  • importation documents;
  • payroll records;
  • transaction-level accounting schedules;
  • correspondence previously submitted to the BIR;
  • affidavits when appropriate; and
  • detailed reconciliations linking the accounting records to the tax returns.

Submit the evidence with a formal transmittal identifying every attachment and obtain proof of submission. The taxpayer should be able to establish exactly what the BIR received and when it received it.

Step 7: Review the assessment for both substantive and procedural defenses

A strong protest normally examines the merits of the tax adjustment and the validity of the assessment process.

Incorrect facts or computations

Check whether the BIR:

  • counted the same income twice;
  • treated balance-sheet movements as taxable income without justification;
  • misread bank deposits or intercompany transfers;
  • disregarded creditable taxes already paid;
  • used figures from a different taxable period;
  • failed to reconcile VAT, withholding-tax, and income-tax data properly;
  • disallowed expenses despite supporting evidence; or
  • applied an incorrect tax rate or classification.

The answer depends on the particular transactions and documents. Never assume that an accounting difference automatically represents taxable income.

Failure to disclose adequate factual and legal bases

Section 228 requires more than a bare amount and demand for payment. The taxpayer must be sufficiently informed of the facts and law underlying the assessment so that an intelligent protest can be made. (E-Library)

In Ortiz Memorial Chapel, the Supreme Court held that general statutory references and unexplained tabulations were insufficient where they did not explain the underlying transactions, computations, and legal theory supporting the assessed deficiencies. The assessments were declared void. (E-Library)

The Supreme Court again emphasized in February 2026 that tax collection must be preceded by a valid assessment and that an assessment must sufficiently disclose its factual and legal bases so the taxpayer can meaningfully respond. (Lawphil)

This does not mean that any imperfect wording automatically invalidates an assessment. Jurisprudence also recognizes substantial compliance where the taxpayer was sufficiently informed in writing of the actual factual and legal bases and was able to make an intelligent protest. (E-Library)

Failure to issue a required PAN

A PAN forms part of the normal statutory assessment process. If no PAN was issued or properly served, determine whether the case falls within one of Section 228's express exceptions. If no exception applies, the defect may affect the validity of the assessment.

Issues with the Letter of Authority

Review the Letter of Authority and the audit history, including:

  • the taxable year or period authorized;
  • taxes covered;
  • revenue officers authorized to conduct the examination;
  • reassignment or substitution of personnel;
  • whether the audit and assessment remained within the authority granted; and
  • whether applicable BIR procedures were followed.

Authority defects can raise significant issues, but their effect is highly fact-specific and should be evaluated under the governing Tax Code provisions, BIR issuances, and Supreme Court cases rather than treated as an automatic cancellation of the assessment.

Prescription

As a general rule, the BIR has three years within which to assess internal revenue taxes, counted under Section 203 from the applicable statutory filing date or actual filing date when the return was filed late. (E-Library)

Important exceptions exist. Under Section 222, a tax may generally be assessed within 10 years after discovery in cases involving a false or fraudulent return with intent to evade tax or failure to file a return. The ordinary assessment period can also be extended by a valid written agreement between the taxpayer and the BIR executed before the applicable assessment period expires. (E-Library)

Do not assume that a document labelled a “waiver” automatically extended the period. The validity, execution, timing, acceptance, and scope of a waiver should be examined carefully. In Ortiz Memorial Chapel, the Supreme Court again stressed that waivers of the statute of limitations must comply with the legal requirements governing extensions of the assessment period. (E-Library)

Step 8: Calendar the 180-day period

Once a valid protest has been filed, maintain a written deadline calendar.

For a request for reconsideration, RR No. 18-2013 generally counts the 180-day period from filing of the protest.

For a request for reinvestigation, the period generally runs from submission of the required supporting documents within the 60-day submission period.

The 180-day period does not mean that the taxpayer automatically wins if the BIR has not acted by then. Instead, it creates procedural choices concerning appeal.

What if the BIR does nothing within 180 days?

If the proper BIR official does not act within the applicable 180-day period, the taxpayer generally has two alternatives:

  1. appeal to the Court of Tax Appeals within 30 days after expiration of the 180-day period; or
  2. wait for the BIR's final decision, then appeal that final decision to the CTA within 30 days from receipt.

RR No. 18-2013 treats the choice between appealing the BIR's inaction and waiting for the eventual final decision as mutually exclusive once the taxpayer has elected and pursued one route.

This is one of the most dangerous stages for deadline mistakes. Do not file a CTA petition based on inaction without first calculating precisely when the applicable 180 days ended and when the corresponding 30-day judicial period expires.

What happens when the BIR issues an FDDA?

The BIR's ruling on the disputed assessment is generally communicated through a Final Decision on Disputed Assessment (FDDA). Under RR No. 18-2013, the FDDA should state the facts and applicable law, regulations, rules, or jurisprudence on which the decision is based and should indicate that it is the final decision.

If the FDDA is issued by a duly authorized representative of the Commissioner, the taxpayer may generally, within 30 days from receipt, either:

  • appeal directly to the CTA; or
  • elevate the protest through a request for reconsideration to the Commissioner of Internal Revenue.

An administrative appeal to the Commissioner at this stage is a reconsideration; RR No. 18-2013 does not permit a new reinvestigation at that level, and the review is limited in accordance with the regulation.

If the Commissioner thereafter denies the protest or administrative appeal, the taxpayer generally has 30 days from receipt of the Commissioner's decision to appeal to the CTA. Filing a motion for reconsideration with the Commissioner does not suspend or restart that 30-day CTA period.

Appeals to the Court of Tax Appeals

Appeals involving disputed BIR assessments ordinarily proceed by petition for review before a Division of the Court of Tax Appeals. Republic Act No. 1125, as amended by Republic Act No. 9282, prescribes the 30-day appeal period from an appealable decision or from expiration of the statutory period for agency action. (E-Library)

CTA proceedings are judicial litigation, not simply another letter to the BIR. The petition, allegations, evidence, verification, attachments, service, filing fees, and current requirements for paper and electronic submissions should be checked against the prevailing Revised Rules of the CTA and the Court's current administrative resolutions. The CTA's official website publishes its current filing and electronic-submission issuances. (Court of Tax Appeals)

A CTA appeal also does not automatically suspend tax collection. Under Republic Act No. 1125, as amended, the CTA may suspend collection when the statutory conditions are met and may require a deposit or surety bond of not more than double the amount claimed. (E-Library)

That makes immediate legal attention important when collection measures are threatened or already underway.

Evidence you should preserve from the beginning

Keep a complete tax-assessment file containing:

  • the Letter of Authority and any replacement or supplemental authority;
  • all requests for accounting records;
  • the Notice of Discrepancy and attachments;
  • minutes or records of the Discussion of Discrepancy;
  • every document submitted during the audit;
  • the PAN and proof of receipt;
  • your PAN reply and proof of filing;
  • the FLD/FAN and Details of Discrepancies;
  • proof of the exact receipt date of the FLD/FAN;
  • the administrative protest and BIR-stamped receiving copy or registered-mail records;
  • the complete reinvestigation submission, if applicable;
  • transmittal letters and attachment lists;
  • the FDDA and proof of receipt;
  • any administrative appeal to the Commissioner;
  • waivers of the statute of limitations;
  • tax returns, audited financial statements, books, invoices, contracts, certificates, schedules, and bank records relevant to the disputed adjustments; and
  • collection letters, warrants, garnishment notices, or levy documents.

BIR Revenue Memorandum Order No. 1-2026 now also requires documentation of taxpayer interactions during the audit, including minutes of the Discussion of Discrepancy, making preservation of the taxpayer's own record of those proceedings especially useful. (Bir Cdn)

Common mistakes that can make a tax dispute much harder

Waiting until the 30th day to start reviewing the assessment

A proper protest often requires reconstruction of several years of accounting records and transaction-level reconciliations. Start immediately.

Treating a PAN response as the formal protest

A PAN reply and an FLD/FAN protest serve different procedural purposes. Receipt of the FLD/FAN ordinarily starts a new 30-day deadline.

Filing a generic denial

A protest that fails to identify the required information or fails to give factual and legal grounds for particular issues may be ineffective.

Choosing reinvestigation but missing the 60-day evidence deadline

If additional evidence is essential to the case, calendar the 60-day submission deadline on the same day the protest is filed.

Forgetting to dispute one tax type or adjustment

An undisputed portion can become final and collectible even while another part of the assessment remains contested.

Filing without proof of receipt

Always retain a stamped receiving copy or the registered-mail evidence recognized by the applicable filing rules.

Assuming BIR silence cancels the assessment

The expiration of 180 days creates appeal options; it does not automatically erase the assessment.

Filing another motion with the CIR after the Commissioner's final denial

RR No. 18-2013 expressly warns that a motion for reconsideration of the Commissioner's denial does not toll the 30-day period for appeal to the CTA.

Assuming a CTA appeal automatically stops collection

It does not. Suspension of collection requires appropriate judicial relief under the governing law. (E-Library)

Deliberately letting the 30-day protest period expire because the assessment “looks void”

The December 2025 Ortiz Memorial Chapel decision recognizes an exception for an assessment void from the beginning, but litigating whether a defect truly reaches that level is far riskier than preserving the normal remedies through a timely protest. (E-Library)

When legal or tax help becomes urgent

Seek prompt professional assistance when:

  • fewer than several days remain before the 30-day protest deadline;
  • the assessed amount is substantial;
  • the assessment alleges fraud, falsity, undeclared sales, or intentional tax evasion;
  • multiple tax types or taxable years are involved;
  • the FLD/FAN appears to have been issued after the assessment period expired;
  • the BIR relied on a waiver of the statute of limitations whose validity is questionable;
  • there are issues involving the Letter of Authority or the identity of the revenue officers who performed the audit;
  • the factual or legal basis of the assessment is unclear;
  • the BIR has issued a Preliminary Collection Letter, Final Notice Before Seizure, warrant of distraint or levy, or garnishment notice;
  • the applicable 180-day period is about to expire;
  • an FDDA or CIR decision has already been received; or
  • you are considering an appeal to the CTA.

The Supreme Court has emphasized that summary collection remedies depend on the existence of an enforceable tax liability and a valid assessment that has passed through the required procedures. A warrant or collection action received while a timely protest or administrative appeal remains unresolved should therefore be examined immediately rather than ignored. (E-Library)

Frequently asked questions

Do I have to pay the full BIR assessment before I can protest it?

Generally, no. Section 228 allows an administrative protest against the FLD/FAN without making prior payment of the disputed amount a condition for filing the protest. If only part of the assessment is disputed, however, the uncontested portion may become final and demandable and should be dealt with separately.

How long do I have to protest an FLD/FAN?

Generally 30 days from receipt, not 30 days from the date appearing on the notice.

What is the difference between reconsideration and reinvestigation?

Reconsideration asks the BIR to re-evaluate the assessment based on the existing record. Reinvestigation relies on newly discovered or additional evidence that the taxpayer intends to submit.

Do I always have 60 days to submit documents after filing a protest?

No. Under RR No. 18-2013, the specific 60-day supporting-document requirement applies to a request for reinvestigation. The regulation states that this period does not apply to a request for reconsideration in the same manner.

Can I send the protest by registered mail?

BIR's prescribed procedures recognize filing an administrative protest personally or by registered mail. For registered mail, the post-office stamp on the envelope is treated as the filing date under RMC No. 15-2020.

Can I just email my protest?

Do not assume ordinary email is sufficient. The published administrative-protest procedure specifically recognizes personal filing and registered mail. Use electronic filing only when a current BIR issuance or other applicable official procedure clearly authorizes it for the particular filing.

What happens if the BIR does not decide my protest within 180 days?

Depending on the type and procedural posture of the protest, you may generally appeal the BIR's inaction to the CTA within 30 days after the applicable 180-day period expires, or elect to wait for the final BIR decision and then appeal within 30 days from receiving it. These options require careful deadline calculation.

What happens if I miss the original 30-day protest deadline?

The general rule is that the assessment becomes final, executory, and demandable.

The Supreme Court's December 3, 2025 decision in Ortiz Memorial Chapel recognizes an exception where the assessment itself is void ab initio for a fundamental defect such as failure to provide the legally required factual and legal bases. Whether an assessment actually falls within that exception requires careful legal analysis; it should not be treated as an extension of the 30-day deadline. (E-Library)

Can I appeal an FDDA directly to the CTA instead of appealing first to the Commissioner?

If the adverse FDDA was issued by the Commissioner's duly authorized representative, RR No. 18-2013 generally permits the taxpayer either to appeal to the CTA within 30 days or elevate the matter through reconsideration to the Commissioner within the same 30-day period.

Does going to the CTA stop the BIR from collecting?

Not automatically. The law allows the CTA to suspend collection under appropriate circumstances, subject to the conditions imposed by the Court, which may include a deposit or surety bond. (E-Library)

Official sources

This article provides general Philippine legal and tax information and is not a substitute for advice based on the particular FLD/FAN, audit records, taxable periods, evidence, and dates of receipt involved in a specific case. Tax-assessment deadlines are particularly strict, and a taxpayer facing an existing assessment should have the actual notices and proof of receipt reviewed promptly. Sources and current procedures checked as of August 25, 2026.

Disclaimer: This content is not legal advice and may involve AI assistance. Information may be inaccurate.

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