Quick answer

To dispute a BIR deficiency assessment, file a valid written protest against the Formal Letter of Demand and Final Assessment Notice (FLD/FAN) within 30 days from receipt. File it with the office of the BIR official who signed the FLD/FAN, following the filing instructions in the notice.

The protest must:

State whether it is a request for reconsideration or a request for reinvestigation.
Identify the assessment notice and its date.
Contest each disputed tax, taxable period, finding, and amount.
State the supporting facts and applicable law, regulations, or jurisprudence for every disputed issue.
If requesting reinvestigation, identify the newly discovered or additional evidence you intend to present.
Be signed by the taxpayer or a properly authorized representative.
Be filed with reliable proof of the filing date.

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

A response to a Preliminary Assessment Notice is not a substitute for this protest. Even if you answered the PAN, you must separately protest the later FLD/FAN.

Identify the document before choosing a remedy

Different BIR documents trigger different remedies:

Document received	What it generally means	Immediate action
Notice of Discrepancy, audit findings, or working papers	The audit is still being discussed	Reply within the period stated in the document, but do not mistake this for the formal Section 228 protest
Preliminary Assessment Notice (PAN)	A proposed deficiency assessment	Submit a written response within 15 days from receipt
FLD/FAN	The formal assessment and demand for payment	File a valid administrative protest within 30 days from receipt
Final Decision on Disputed Assessment (FDDA)	The BIR has decided the protest	Choose the proper administrative appeal, if available, or appeal to the CTA within 30 days
Collection letter, Final Notice Before Seizure, warrant of distraint or levy, or garnishment notice	The BIR considers the liability collectible, or collection is already underway	Obtain tax-litigation advice immediately; the document may affect the CTA deadline depending on its wording and procedural history

This procedure applies to deficiency assessments of national internal revenue taxes under Section 228 of the National Internal Revenue Code. It does not necessarily apply to local taxes, real-property taxes, customs duties, refund denials, or amounts admitted as payable in the taxpayer’s own return. A document described as an “RPS Assessment” may also be a collection communication rather than an audit assessment.

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

The deadlines that control the case

Treat these as calendar-day deadlines and count conservatively. Do not assume that settlement discussions, requests for clarification, or informal communications extend them.

Event	Period	Reckoning point	Main consequence of missing it
Response to PAN	15 days	Receipt of PAN	BIR may proceed to the FLD/FAN
Administrative protest against FLD/FAN	30 days	Receipt of FLD/FAN	Assessment may become final, executory, and demandable
Supporting documents for reinvestigation	60 days	Filing of protest	Assessment may become final and the BIR may reject additional evidence
BIR action on reconsideration	180 days	Generally, filing of the protest	Taxpayer must choose whether to appeal the inaction or await a final decision
BIR action on reinvestigation	180 days	Submission of the required supporting documents	Same choice after inaction
Appeal from FDDA or final denial	30 days	Receipt of decision	Decision and assessment may become final
CTA appeal from inaction	30 days	Lapse of the applicable 180-day period	Taxpayer loses the immediate inaction appeal if not filed, but may instead have elected to await a final decision

The 30-day administrative protest period is ordinarily not extendible. A special BIR issuance may occasionally extend deadlines for specifically affected taxpayers, such as during a declared emergency, but do not rely on an extension unless an official issuance clearly covers the taxpayer, office, document, and due date.

A CTA petition is also generally due within 30 days. Court rules permit limited relief through a timely motion for an additional period in appropriate cases, but an extension is not automatic and should never be treated as a filing strategy.

Respond to the PAN, even though it is not yet the formal protest

Under Revenue Regulations No. 18-2013, a taxpayer ordinarily has 15 days from receipt of the PAN to respond. The response should address every proposed adjustment, provide reconciliations, identify incorrect assumptions, and attach available records.

The BIR may issue an FLD/FAN without a PAN in these statutory situations:

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 for excess creditable withholding tax and also carried over and applied the same amount to the following taxable year.
Excise tax due on excisable articles was not paid.
An article purchased or imported by an exempt person was sold, traded, or transferred to a non-exempt person.

Outside these exceptions, failure to give the taxpayer a meaningful opportunity to respond to the PAN can be a due-process issue. The Supreme Court has emphasized that the taxpayer must actually have the 15-day opportunity before the FLD/FAN is issued in cases where a PAN is required. See Commissioner of Internal Revenue v. Avon Products Manufacturing, Inc..

Even if the PAN, its service, or its timing appears defective, do not ignore the FLD/FAN. Raise the defect in a timely protest.

Choose the correct kind of protest

Request for reconsideration

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

The special 60-day period for supporting documents does not apply to reconsideration. That does not make reconsideration a device for submitting evidence late.

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. All relevant supporting documents must then be submitted within 60 days from filing the protest.

The BIR defines relevant documents as those needed to support the legal and factual grounds selected by the taxpayer. Evaluation may be confined to documents submitted within the prescribed period.

Consideration	Reconsideration	Reinvestigation
Record used	Existing BIR record	Existing record plus identified new or additional evidence
New documents anticipated	No	Yes
60-day document deadline	No	Yes
Typical use	Legal interpretation, computational error, or existing records overlooked	Missing third-party records, contracts, certifications, reconciliations, or other additional proof

State the choice expressly. A letter that merely says the taxpayer disagrees or is still compiling documents may not be a valid protest. The Supreme Court applied the formal requirements strictly in Commissioner of Internal Revenue v. Citysuper, Inc..

What the protest letter should contain

A careful protest should include the following:

Taxpayer identification
- Registered name, address, TIN, contact information, and BIR registration details.
- Name and authority of the representative, if any.
Assessment identification
- FLD/FAN date, assessment numbers, tax types, taxable periods, and amounts.
- Actual date and manner of receipt.
- A copy of the complete FLD/FAN and all attachments.
Express nature of the protest
- State “request for reconsideration” or “request for reinvestigation.”
- For reinvestigation, list the newly discovered or additional evidence to be submitted.
Issue-by-issue objections
- Identify each disputed finding separately.
- State the relevant facts.
- Cite the applicable Tax Code provision, regulation, controlling decision, or other legal authority.
- Explain why the BIR’s factual premise, legal interpretation, classification, computation, or penalty is incorrect.
- Provide a corrected computation when appropriate.
Treatment of undisputed items
- Clearly identify any accepted finding.
- State whether the undisputed amount has been or will be paid, with proof when available.
Requested relief
- Ask that the disputed assessment be cancelled or reduced to the supported amount.
- Request an FDDA stating the factual and legal grounds for the decision.
Attachments and index
- Number every annex.
- Provide an index explaining which issue each document supports.
- For reinvestigation, state whether the initial filing is complete or identify documents to follow within the 60-day period.
Signature and authority
- The taxpayer or authorized representative should sign.
- Attach the appropriate proof of authority, such as a special power of attorney or corporate authorization, where applicable.

Do not rely on a blanket statement that the assessment is “unfair,” “incorrect,” or “unsupported.” Attaching tax returns or accounting records without explaining their relevance is also risky.

If an FLD/FAN contains several findings, an issue not specifically disputed with supporting facts and legal grounds may be treated as undisputed. The amount attributable to that issue can become final and collectible even while other issues remain under protest.

Where and how to file

File the protest with the office of the Commissioner’s duly authorized representative who signed the FLD/FAN. Current BIR audit guidance generally routes protests through the office of the concerned Regional Director or Assistant Commissioner for the Large Taxpayers Service, as applicable. The notice itself and the taxpayer’s registration or large-taxpayer status determine the precise receiving office.

This filing route is reflected in Revenue Memorandum Circular No. 11-2014 and the BIR’s updated audit procedures under Revenue Memorandum Order No. 6-2023.

For a defensible filing:

Confirm the proper receiving office before the deadline.
Bring enough complete copies for the BIR and the taxpayer.
Obtain a receiving stamp showing the date, office, and receiving personnel.
Keep the stamped copy and any routing or acknowledgment slip.
If an authorized delivery method is used, preserve the registry receipt, tracking record, proof of delivery, and the complete contents sent.
Do not assume that ordinary email, a message to the examiner, or an upload to a general BIR facility constitutes a valid protest unless the BIR has expressly authorized that filing channel for the case.

Filing with the wrong office can be fatal. An administrative appeal from a decision of the Commissioner’s authorized representative must be filed with the Office of the Commissioner.

Review both the substance and validity of the assessment

A protest should examine more than the BIR’s arithmetic.

Written factual and legal bases

The FLD/FAN must state the facts and the law, regulations, or jurisprudence on which the assessment is based. A bare computation or unexplained conclusion may violate Section 228. The formal assessment should also communicate an actual demand for payment, including the amount and the applicable payment period.

Proper sequence and opportunity to be heard

Unless a statutory PAN exception applies, the BIR must give the taxpayer a genuine opportunity to respond to the proposed assessment before issuing the final assessment. The BIR must also meaningfully consider the taxpayer’s explanations and evidence.

Proper authority

Review the Letter of Authority or electronic Letter of Authority, the officers assigned, the taxable period and taxes covered, any reassignment or replacement authority, and the authority of the official who issued the assessment. Whether a defect invalidates the assessment depends on the governing issuance and the documents.

Assessment prescription

The general rule under Section 203 of the Tax Code is that an assessment must be made within three years from the statutory filing deadline or actual filing of the return, whichever is later. Different rules may apply to a false or fraudulent return made with intent to evade tax, failure to file a return, or a valid written waiver. Prescription analysis is document-intensive and should account for the exact return, filing date, assessment service, and every waiver.

Proper service

BIR notices may be served personally or, when permitted, through substituted service or mail. Preserve evidence concerning:

The registered and known addresses at the time.
Who received the document and that person’s position or authority.
The envelope, registry notice, postmark, tracking history, and return card.
The date of the first postmaster notice.
Reception, security, and mailroom logs.
Any address update previously filed with the BIR.

Under Revenue Memorandum Order No. 40-2019, BIR personnel use specific completion rules for personal, substituted, registered-mail, and ordinary-mail service. A taxpayer should not assume that refusing or delaying pickup prevents service. Conversely, the Supreme Court has repeatedly required the BIR to prove proper service. See Commissioner of Internal Revenue v. Fort 1 Global City Center, Inc..

A suspected void assessment should still be protested on time. Do not gamble the case on a service or due-process defense without preserving the administrative remedy.

Evidence to preserve

Create a complete assessment file containing:

Letter of Authority or eLA, replacements, and related authority documents.
Notices of Discrepancy, PAN, FLD/FAN, FDDA, collection letters, warrants, and every attachment.
Envelopes, delivery records, registry notices, receiving logs, and proof of actual receipt.
All responses, protests, submissions, transmittal letters, and stamped receiving copies.
Tax returns, amended returns, filing confirmations, and payment records.
Books of accounts, ledgers, trial balances, audit working papers, and reconciliations.
Invoices, withholding certificates, contracts, bank records, import documents, payroll records, and other source documents relevant to the findings.
Written requests from revenue officers and a log of what was submitted, when, and to whom.
Minutes or written confirmation of conferences and settlement discussions.
Corporate authority or special power of attorney for representatives.
A master deadline sheet showing receipt, filing, document-submission, 180-day, and appeal dates.

Keep original records intact. Work from indexed copies and record any document delivered to the BIR.

What happens after filing

If the protest is granted or partly granted

The BIR should issue an FDDA communicating its resolution. Any accepted or undisputed amount may be paid separately. Preserve the relevant payment form and proof of payment.

If an authorized representative denies the protest

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

File a petition for review with the Court of Tax Appeals; or
Elevate the matter to the Commissioner through a request for reconsideration.

The administrative appeal to the Commissioner cannot be a reinvestigation. Only issues covered by the authorized representative’s decision will be entertained. Choosing an administrative appeal postpones the CTA route until the Commissioner decides or the applicable inaction remedy arises.

If the Commissioner denies the protest or administrative appeal

File a petition for review with the CTA within 30 days from receipt. A further motion for reconsideration filed with the Commissioner does not stop or restart that CTA deadline.

If the BIR does not act within 180 days

The taxpayer has two mutually exclusive choices:

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

Once the taxpayer appeals the inaction, the taxpayer cannot also await and later appeal the eventual administrative decision. If the taxpayer chooses to wait, communications should be consistent with that choice. The Supreme Court confirmed these alternatives in Commissioner of Internal Revenue v. GJM Philippines Manufacturing, Inc..

The precise start of the 180-day period matters. For reconsideration, it is generally counted from filing of the protest. For reinvestigation, it is counted from submission of the required supporting documents. Do not calculate it merely from the assessment date.

Appealing to the Court of Tax Appeals

An appeal is commenced by filing a petition for review with a CTA Division. It must comply with the Revised Rules of the Court of Tax Appeals, including verification, certification against forum shopping, required attachments, copies, and docket fees.

The CTA filing should normally be handled by Philippine tax-litigation counsel. The 30-day period is jurisdictional in character, and a defective or late petition may be dismissed without reaching the assessment’s merits.

An appeal does not automatically stop collection. Under Republic Act No. 9282 and the CTA Rules, the taxpayer may ask the CTA to suspend collection when collection may jeopardize the interests of the Government or the taxpayer. The court may require a cash deposit or an acceptable surety bond of not more than twice the disputed amount.

A special point for consolidated assessments

The BIR’s 2026 single-instance audit framework allows consolidation of certain pending audit cases, including limited situations where separate FANs have not yet become final. If the BIR serves a Consolidated FAN, do not assume that earlier protests, dates, or computations remain controlling without review.

The applicable response or protest period may run from actual receipt of the consolidated notice, subject to the conditions and safeguards in Revenue Memorandum Order No. 6-2026. Compare the consolidated FAN with every earlier assessment and immediately confirm which notices were replaced, which findings were carried forward, and the new deadline.

Common mistakes

Treating a PAN response as the protest against the FLD/FAN.
Waiting for a meeting with the examiner while the 30-day period runs.
Filing a general objection without identifying reconsideration or reinvestigation.
Requesting reinvestigation without identifying the additional evidence.
Failing to dispute every adjustment separately.
Citing legal conclusions without stating the supporting facts.
Submitting attachments without explaining which issue each document proves.
Filing with the examiner or wrong BIR office instead of the office of the authorized signatory.
Relying only on email or an unacknowledged courier delivery.
Missing the 60-day reinvestigation document deadline.
Counting the 180 days from the wrong event.
Filing another motion with the Commissioner and assuming it suspends the CTA deadline.
Assuming that a void or obviously incorrect assessment can simply be ignored.
Assuming a CTA appeal automatically stops collection.
Failing to preserve the envelope, registry notice, and proof of receipt.

When professional help is urgent

Consult a Philippine tax lawyer immediately if:

Fewer than ten days remain before a protest or CTA deadline.
The assessment has become final because of an apparent missed deadline.
You received an FDDA, Final Notice Before Seizure, warrant of distraint or levy, garnishment notice, or bank demand.
The BIR is collecting while the protest or appeal period is disputed.
Fraud, deliberate falsity, tax evasion, or criminal referral is alleged.
The assessment covers several tax types or taxable years.
A waiver, replacement eLA, consolidated FAN, or disputed service is involved.
The BIR assessed a large amount relative to the taxpayer’s ability to operate.
Important documents are missing, held by third parties, or inconsistent with filed returns.
The BIR communication is unclear about whether it is an assessment, an FDDA, or a collection decision.

Frequently asked questions

Must I pay the assessment before filing an administrative protest?

Generally, no prepayment is required to file a Section 228 protest. However, any undisputed portion can become final and collectible. A later CTA appeal also does not automatically suspend collection.

Can I protest only the basic tax and leave the penalties for later?

That is risky. Address the basic tax, surcharge, interest, and other assessed amounts expressly. An unchallenged item may be treated as undisputed.

Can the protest be a short “protective” letter followed by arguments later?

A bare protective letter may be void. The initial protest must already state its nature, identify the assessment, and provide the factual and legal grounds for every disputed issue. A reinvestigation permits supporting documents within 60 days, but it does not excuse a legally deficient initial protest.

Which is safer: reconsideration or reinvestigation?

Neither is automatically safer. Use reconsideration only when the existing BIR record is sufficient. Use reinvestigation when additional evidence is genuinely needed and can be identified and submitted within 60 days.

What if the BIR assessment does not explain its basis?

Failure to state the factual and legal grounds can make an assessment void. Raise that defect—and all available substantive defenses—in a timely protest rather than ignoring the notice.

What if I never personally received the assessment?

Service may have been made on an authorized representative, through proper substituted service, or by mail. Obtain the BIR records and preserve all address and delivery evidence. Do not assume there was no effective service merely because the owner or responsible officer did not personally see the document.

What if the BIR stays silent after 180 days?

Either appeal the inaction to the CTA within the next 30 days or await the final decision and appeal within 30 days from receiving it. The choices are mutually exclusive.

Can I negotiate a settlement while protesting?

Discussions may continue, but they do not suspend statutory deadlines. A compromise or abatement also has separate statutory requirements and approval procedures. Continue protecting the protest and appeal periods unless a valid final settlement has been completed.

Do I need a lawyer for the BIR protest?

The taxpayer, an authorized representative, or a tax agent may file the administrative protest. Legal and accounting assistance is strongly advisable where the amount, evidence, procedural defects, or possible CTA appeal is significant. CTA litigation should be handled by qualified counsel.

Official sources

This article provides general legal information, not legal or tax advice for a particular assessment. Outcomes depend on the notices, proof of service, audit authority, tax returns, evidence, and procedural history. Official sources and current procedures were checked as of 4 August 2026.