Quick answer

To protest a Bureau of Internal Revenue tax assessment, file a valid 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 — asks the BIR to reevaluate the assessment using the existing records; or
Request for reinvestigation — asks for a new evaluation based on newly discovered or additional evidence.

If you choose reinvestigation, submit all relevant supporting documents within 60 days from filing the protest. Missing the 30-day protest deadline—or, for reinvestigation, the 60-day document deadline—can make the assessment final, executory, and demandable.

A reply to a Preliminary Assessment Notice is important, but it is not a substitute for protesting the later FLD/FAN. Likewise, informal discussions, requests for copies, payment proposals, and letters that do not satisfy the protest requirements may not stop the assessment from becoming final.

First identify the document you received

BIR audit papers have different legal effects and deadlines.

Notice of Discrepancy

A Notice of Discrepancy ordinarily invites the taxpayer to discuss findings and submit explanations or records. Respond promptly, but do not mistake participation in this stage for a formal protest under Section 228 of the National Internal Revenue Code.

Preliminary Assessment Notice

A Preliminary Assessment Notice or PAN states the proposed deficiencies and their factual and legal bases. Under Revenue Regulations No. 18-2013, the taxpayer generally has 15 days from receipt to respond.

Use the PAN response to challenge factual errors, legal conclusions, computations, audit authority, prescription, and procedural defects. Attach documents that can resolve the findings before a final assessment is issued.

A PAN is generally required, but Section 228 permits an FLD/FAN to be issued without one in specified cases, including certain mathematical errors apparent from the return, discrepancies between tax withheld and tax remitted, and unpaid excise tax.

Formal Letter of Demand and Final Assessment Notice

The FLD/FAN is the assessment that must be administratively protested within 30 days from receipt. Filing only a PAN response does not preserve the right to dispute the FLD/FAN.

Final Decision on Disputed Assessment

A Final Decision on Disputed Assessment or FDDA is the BIR’s decision on the protest. Depending on who issued it and the procedural stage, the remedy may be an administrative appeal to the Commissioner of Internal Revenue or a petition for review before the Court of Tax Appeals.

Do not rely solely on the document’s title. Examine its language and effect. A letter that clearly denies the protest with finality and demands payment may start the period for the next remedy even if it uses a different label.

The 30-day deadline is critical

Count the 30-day protest period from the taxpayer’s actual or legally effective receipt of the FLD/FAN. Preserve the envelope, registry notice, acknowledgment receipt, courier tracking, email metadata if applicable, and the identity and authority of the recipient.

If the taxpayer is a corporation, receipt by an employee or another person can create a dispute over whether service was valid. The governing regulations prescribe modes of service and, for personal delivery, require information concerning the recipient’s identity, designation, and authority. The Supreme Court has treated proper service as part of the taxpayer’s right to be informed and heard, although the outcome of a service objection depends on the facts and the taxpayer’s actual opportunity to respond.

Because a deadline dispute can dispose of the entire case, calculate conservatively. Do not wait for the last day.

Choose the correct type of protest

Request for reconsideration

A request for reconsideration asks the BIR to reevaluate the assessment based on the records already available. It does not depend on newly discovered or additional evidence.

This may be appropriate when the dispute is primarily legal or when the existing audit record already contains everything needed to decide the case—for example:

The assessment was issued after the applicable prescriptive period;
The BIR applied the wrong tax provision or rate;
The same item was assessed twice;
The computation is inconsistent with records already submitted;
The assessment failed to state adequate factual or legal grounds; or
The officials who issued the assessment lacked the required authority.

The special 60-day deadline for additional supporting documents does not apply in the same way to a reconsideration under RR No. 18-2013. Nevertheless, identify and attach the existing records on which the arguments rely.

Request for reinvestigation

A request for reinvestigation seeks a new examination based on newly discovered or additional evidence. It may be appropriate when further invoices, contracts, reconciliations, withholding certificates, bank records, accounting schedules, or third-party confirmations are necessary.

All relevant supporting documents must be submitted within 60 days from filing the protest. Failure to comply can bar the taxpayer from disputing the assessment through newly discovered or additional evidence and result in denial of the protest.

Choose deliberately. Calling a submission “reconsideration” while asking the BIR to examine substantial new evidence may create an avoidable procedural dispute.

What a valid protest should contain

Under RR No. 18-2013, the protest should state:

Whether it is a request for reconsideration or reinvestigation;
The date of the assessment notice;
The specific findings and amounts being disputed;
The material facts supporting the taxpayer’s position;
The applicable statutes, regulations, and jurisprudence; and
For reinvestigation, the newly discovered or additional evidence intended to be submitted.

Address every disputed tax, taxable period, issue, and component. If several issues are assessed but only some are properly challenged, the unchallenged portions may become final, executory, and demandable. The same risk exists when an issue is nominally disputed but the protest fails to provide supporting facts and legal grounds.

A useful structure is:

Identification of the taxpayer and assessment;
Date and manner of receipt;
Type of protest selected;
Summary of relief requested;
Separate section for each assessed issue;
Statement of facts for each issue;
Legal basis;
Computation of the correct amount, if any;
List of attachments;
Reservation concerning documents to follow, if reinvestigation was chosen; and
Request for cancellation or appropriate reduction of the assessment.

A bare statement that the assessment is “incorrect,” “unfair,” or “unsupported” is dangerous. The protest should permit the BIR to understand and decide each objection.

Review the assessment for substantive and procedural defenses

Factual and accounting errors

Reconcile the assessment against the taxpayer’s:

Returns and amendments;
Audited financial statements;
General ledger and trial balance;
Sales, purchase, and subsidiary ledgers;
Invoices and other source documents;
Withholding tax returns and certificates;
Bank records;
Importation records;
Contracts; and
Prior payments and tax credits.

Prepare a traceable reconciliation rather than submitting an unexplained bundle of documents.

Wrong legal characterization

Determine whether the BIR used the correct tax type, taxable base, rate, sourcing rule, timing rule, exemption requirement, or withholding treatment. Quote the controlling provision and explain how it applies to the documented transaction.

Prescription

As a general rule, an internal revenue tax must be assessed within three years under Section 203 of the Tax Code, subject to statutory rules on when the period begins and exceptions.

A longer period may apply in cases such as a false or fraudulent return with intent to evade tax or failure to file a return. Written waivers may also affect the deadline if legally valid. Prescription analysis is document-sensitive: verify the filing date, return involved, issuance and release of the assessment, alleged fraud or non-filing, and every waiver.

Do not assume that any error automatically authorizes the extraordinary period. The characterization and proof required depend on the applicable law and jurisprudence.

Lack of adequate factual or legal basis

Section 228 requires the taxpayer to be informed in writing of the law and facts on which the assessment is made; otherwise, the assessment may be void. A list of amounts or generic conclusion may be insufficient if it does not enable an intelligent protest.

However, courts examine the complete written communications and circumstances. Do not assume that every imperfect explanation automatically invalidates the assessment.

Defective notice or service

Check whether the required PAN was issued, whether a statutory exception applied, whether the taxpayer received a meaningful opportunity to respond, and whether the FLD/FAN was served through an authorized mode.

The Supreme Court has repeatedly recognized the PAN and written-basis requirements as important elements of assessment due process. Recent decisions also show that service disputes are highly fact-specific, making proof of receipt and recipient authority essential.

Audit authority

Examine the Letter of Authority and related records. Depending on the facts, relevant questions may include whether the audit was conducted by properly authorized revenue officers, whether substitutions were formally authorized, whether the correct taxpayer, tax types, and periods were covered, and whether the assessment was issued by a duly authorized official.

How to file and prove timely submission

Follow the filing instructions stated in the assessment and applicable BIR rules. Ordinarily, the protest should be filed with the BIR office or official that issued the FLD/FAN, subject to the Bureau’s organizational and procedural requirements.

Keep:

A complete signed copy of the protest and attachments;
The receiving copy bearing the BIR date stamp, name, and office of the recipient;
Registry receipt, proof of mailing, or authorized courier proof, if applicable;
Electronic acknowledgment, if an authorized electronic channel was used;
Board resolution, secretary’s certificate, special power of attorney, or other proof of representative authority;
Index and page count of all documents; and
Evidence showing the date of receipt of the assessment.

Do not rely on an unacknowledged email, an oral assurance from an examiner, or an informal turnover of documents. The taxpayer should be able to prove what was filed, where, when, and under whose authority.

What happens after the protest

Decision by a duly authorized BIR representative

If a duly authorized representative of the Commissioner denies the protest in whole or in part, the taxpayer generally has 30 days from receipt to choose between:

Appealing to the Court of Tax Appeals; or
Elevating the protest to the Commissioner through a request for reconsideration.

Only reconsideration—not another reinvestigation—is allowed at this administrative-appeal stage, and the Commissioner generally entertains only issues covered by the representative’s decision.

The correct remedy depends on the identity and authority of the official who issued the decision. Confirm this before filing.

Decision by the Commissioner

If the Commissioner denies the protest or administrative appeal, the taxpayer may file a petition for review with the CTA within 30 days from receipt. Filing another motion for reconsideration with the Commissioner does not suspend or restart that 30-day judicial appeal period.

BIR inaction for 180 days

The starting point depends on the type of protest:

For reconsideration, RR No. 18-2013 counts the 180 days from filing the protest.
For reinvestigation, it counts from submission of the required documents within the 60-day period.

After the 180-day period expires without action, the taxpayer may:

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

The Supreme Court confirmed these options in Lascona Land Co., Inc. v. Commissioner of Internal Revenue. They are mutually exclusive: once the taxpayer appeals the inaction, the taxpayer cannot also wait for and separately appeal the later administrative decision.

The dates must be calculated from the actual record. An incorrect choice or late petition can permanently lose CTA review.

Appealing to the Court of Tax Appeals

Disputed BIR assessments fall within the jurisdiction of the CTA under Republic Act No. 1125, as amended by Republic Act No. 9282, and the Revised Rules of the Court of Tax Appeals.

A CTA case begins with a petition for review complying with the governing rules on allegations, verification, certification against forum shopping, attachments, service, legal fees, and proof of authority. The administrative protest, assessment notices, proof of receipt, decisions, and supporting records are central parts of the case.

CTA litigation has jurisdictional deadlines and technical requirements. Engage tax counsel early enough to examine the administrative record and prepare the petition—not only when the 30-day period is about to expire.

Does a protest automatically stop collection?

Do not assume that filing a protest or CTA case automatically prevents all collection action.

Under the Tax Code and CTA law, tax collection is generally not suspended merely because a judicial proceeding is pending. The CTA may suspend collection when collection could jeopardize the interests of the government or the taxpayer, subject to statutory conditions. The court may require a deposit or bond, although the law also addresses circumstances in which such security should not be required.

If the BIR issues a collection letter, preliminary collection notice, final notice before seizure, warrant of distraint or levy, garnishment notice, or similar enforcement document while the assessment is disputed, obtain immediate advice. The correct remedy depends on whether the assessment became final, whether the protest or appeal was timely, and whether collection should be restrained.

Evidence to preserve

Keep the complete audit and assessment file, including:

Letter of Authority and amendments or replacement authorities;
Notices, letters, emails, envelopes, registry cards, and courier records;
PAN, PAN response, FLD/FAN, protest, FDDA, and collection notices;
Proof of every date of receipt and filing;
Records of conferences and document submissions;
Tax returns, financial statements, ledgers, invoices, contracts, and bank records;
Electronic accounting data in its original format;
Reconciliations and computations;
Proof of payment and tax credits;
Waivers of the statute of limitations; and
Proof of the authority of every person who signed, received, or filed documents.

Maintain an event chronology with separate columns for the document date, receipt date, filing deadline, actual filing date, and proof.

Common mistakes

Treating a PAN response as the protest against the FLD/FAN;
Counting from the date printed on the notice instead of properly determining the receipt date;
Waiting for an informal conference while the 30-day period runs;
Failing to specify reconsideration or reinvestigation;
Choosing reconsideration while depending on substantial new evidence;
Missing the 60-day supporting-document deadline for reinvestigation;
Disputing only the total amount without addressing every assessment issue;
Filing documents without a receiving copy or other reliable proof;
Assuming repeated requests for reconsideration restart an appeal period;
Waiting beyond the CTA deadline after receiving a final denial;
Paying or signing a waiver, settlement, or compromise document without understanding its effect; and
Ignoring collection notices because a protest was previously filed.

When legal or tax help is urgent

Seek immediate professional assistance when:

Fewer than 10 days remain before a protest or CTA deadline;
The date or validity of service is disputed;
The assessment is already described as final, executory, or delinquent;
The BIR has issued a warrant, garnishment, levy, or seizure notice;
Fraud, willful failure to file, or tax-evasion allegations appear;
The ordinary assessment period may have expired;
The audit authority or assessment signatory is questionable;
Significant new documents require a reinvestigation;
The assessment involves several tax types or taxable years;
A BIR official has denied the protest; or
The taxpayer is considering compromise, abatement, or payment while preserving legal remedies.

Frequently asked questions

Can I protest a Notice of Discrepancy?

You may and generally should explain the discrepancy and submit records, but that submission is not the statutory protest against an FLD/FAN. Continue monitoring for later notices and observe each separate deadline.

Is responding to the PAN enough?

No. If the BIR later issues an FLD/FAN, file a separate valid protest within 30 days from receipt.

Can I submit the evidence after 60 days?

For reinvestigation, the regulations require all relevant supporting documents within 60 days from filing the protest. Late submission may not preserve the right to rely on additional evidence. Do not assume the examiner can extend a statutory or regulatory deadline through an informal assurance.

Should I choose reconsideration or reinvestigation?

Choose reconsideration when the case can be resolved from the existing record. Choose reinvestigation when newly discovered or additional evidence is necessary. The substance of the request and evidence—not merely its label—should guide the decision.

What if I agree with only part of the assessment?

Identify the agreed and disputed portions precisely. Issues not validly protested may become final and collectible. Payment of an undisputed amount should be properly documented and coordinated so it is credited to the correct tax, period, and assessment.

Must I pay before appealing to the CTA?

A deficiency-assessment appeal is not generally structured as an ordinary “pay first, litigate later” refund claim. However, collection is not automatically suspended, and a request to suspend collection may involve statutory security requirements. Obtain advice based on the assessment and collection posture.

What if the BIR does nothing for 180 days?

You may appeal the inaction to the CTA during the following 30 days or wait for the final administrative decision and appeal within 30 days from receiving it. Because the options are mutually exclusive and the starting date can be disputed, decide with counsel before the 180-day period expires.

Can the BIR and taxpayer settle the assessment?

The Tax Code permits compromise in specified circumstances and abatement or cancellation in certain situations, subject to legal standards and approval authority. A compromise request does not necessarily replace or suspend protest and appeal deadlines. Preserve the contested-assessment remedies unless a binding resolution has been completed.

Official legal references

This article provides general legal information, not legal or tax advice for a particular assessment. Deadlines and remedies depend on the documents, issuing official, manner of service, and procedural history. Current law and official sources were checked as of August 25, 2026.