Quick answer

If you receive a Formal Letter of Demand and Final Assessment Notice (FLD/FAN) from the Bureau of Internal Revenue (BIR) and disagree with it, you generally have 30 days from receipt to file a valid administrative protest. The protest must be in writing and must clearly state whether you are asking for reconsideration or reinvestigation, identify the assessment being challenged, and state the factual and legal grounds for disputing each issue. A vague letter saying that you “disagree” with the assessment may not be enough. (Bir Cdn)

The distinction between reconsideration and reinvestigation is important:

Reconsideration asks the BIR to re-evaluate the assessment using the records and evidence already available.
Reinvestigation is appropriate when you intend to present newly discovered or additional evidence. If you choose this remedy, the relevant supporting documents must generally be submitted within 60 days from filing the protest. (Bir Cdn)

Missing the applicable 30-day or 60-day deadline can cause the assessment, or particular issues within it, to become final, executory, and demandable. Once an assessment has reached that stage, the taxpayer's remedies become much narrower. (Bir Cdn)

A response to a Preliminary Assessment Notice (PAN) should not be confused with the protest against the FLD/FAN. Under current BIR rules, a PAN response may be filed within 15 days from receipt, but the administrative protest that protects the taxpayer's remedy under the assessment process is the protest against the FLD/FAN within the separate 30-day period. BIR Revenue Memorandum Order No. 26-2016 expressly describes a protest against the PAN as optional rather than mandatory. (Bir Cdn)

Because tax-assessment deadlines are short and are usually counted from receipt of a particular document, immediately record when, where, and by whom every BIR notice was received.

The basic deadline map

Stage	General deadline or rule
Preliminary Assessment Notice (PAN)	Respond within 15 days from receipt if you wish to contest the proposed findings. (Bir Cdn)
FLD/FAN	File a valid administrative protest within 30 days from receipt. (Bir Cdn)
Reinvestigation	Submit all relevant supporting documents within 60 days from filing the protest. (Bir Cdn)
Reconsideration	The special 60-day supporting-document requirement applicable to reinvestigation does not apply in the same way because reconsideration is based on the existing record. (Bir Cdn)
BIR inaction	The rules provide a 180-day decision period, with the starting point depending on whether the protest is a reconsideration or reinvestigation. After the applicable 180-day period expires, the taxpayer faces an important choice concerning appeal to the Court of Tax Appeals (CTA). (Bir Cdn)
Adverse FDDA issued by an authorized BIR representative	Generally, within 30 days from receipt, either appeal to the CTA or elevate the matter administratively to the Commissioner of Internal Revenue (CIR) through a request for reconsideration. (Bir Cdn)
CIR's final denial	Generally, appeal to the CTA within 30 days from receipt. (Bir Cdn)

These periods should be treated conservatively. Do not deliberately wait until the last day, particularly if there is uncertainty about the correct BIR office, method of filing, service date, holidays, work suspensions, or the authority of the person who received the notice.

Do not confuse a PAN with the final assessment

A PAN informs the taxpayer of the BIR's proposed deficiency findings before the formal assessment is issued. Under Revenue Regulations No. 18-2013, the PAN should show in detail the facts and the law, rules, regulations, or jurisprudence supporting the proposed assessment. The taxpayer generally has 15 days from receipt to respond. (Bir Cdn)

A PAN is not required in every case. Section 228 of the Tax Code and Revenue Regulations No. 18-2013 recognize exceptions, including assessments arising from:

a mathematical error apparent on the face of the tax return;
a discrepancy between tax withheld and the amount actually remitted by a withholding agent;
certain cases where excess creditable withholding tax was both claimed for refund or tax credit and carried forward;
unpaid excise tax; and
transfers to non-exempt persons of articles purchased or imported by an exempt person under the circumstances covered by the law. (Bir Cdn)

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

Even when a PAN has been answered, carefully watch for the FLD/FAN. A detailed PAN reply does not eliminate the need to file a timely protest against the FLD/FAN once the formal assessment is received.

Step 1: Establish the exact date of receipt

The protest period generally runs from receipt, not simply from the date printed on the assessment.

Preserve evidence showing when the PAN, FLD/FAN, FDDA, and any subsequent BIR communication were actually received. Useful evidence can include:

the original envelope;
registered-mail records;
courier tracking information;
the receiving stamp or delivery receipt;
an office receiving log;
an email or electronic-transmission record, where applicable;
the identity and position of the person who received the notice; and
documents showing the taxpayer's registered BIR address at the relevant time.

BIR guidance provides that assessment notices are ordinarily served first at the taxpayer's registered address, or may be served simultaneously at the registered and known addresses. Whether service was legally effective can nevertheless depend on the particular facts. (Bir Cdn)

If the date or validity of service is disputed, do not assume that this automatically gives you additional time. Where possible, file based on the earliest defensible deadline while preserving the objection to improper service.

Step 2: Review whether the assessment itself satisfies due-process requirements

Section 228 requires the taxpayer to be informed in writing of the law and facts on which the assessment is made. Revenue Regulations No. 18-2013 likewise states that the FLD/FAN must state the factual and legal bases of the assessment; otherwise, the assessment may be void. (Bir Cdn)

Review the assessment package closely. Among other things, determine:

which taxable periods are covered;
which tax types are being assessed;
how the BIR computed the alleged deficiency;
which transactions or adjustments produced the deficiency;
which provisions of law, regulations, or jurisprudence the BIR relies upon;
whether penalties and interest have been computed on the proper bases;
whether the notice was issued and served through the proper process; and
whether there may be a prescription issue concerning the BIR's authority to assess.

Prescription questions can be highly fact-specific. Waivers, allegedly false or fraudulent returns, failure to file returns, amended returns, and other circumstances may materially change the analysis. A taxpayer should therefore avoid declaring an assessment “prescribed” solely by counting years from the original return without reviewing the complete audit record.

Procedural defects also differ in legal significance. Some violations can invalidate an assessment, while others may not. The safest approach is to identify each defect precisely and connect it to the governing provision rather than broadly alleging “denial of due process.”

Step 3: Choose between reconsideration and reinvestigation

The choice must be made deliberately.

Request for reconsideration

Use reconsideration when the dispute can be resolved by re-evaluating the assessment on the basis of the documents and evidence already forming part of the record.

Typical arguments might concern:

incorrect interpretation of the law;
mathematical or computational treatment;
an erroneous characterization of a transaction;
evidence already submitted during the audit but allegedly disregarded; or
conclusions that do not follow from the documents already before the BIR.

Request for reinvestigation

Use reinvestigation when you need the BIR to consider newly discovered or additional evidence or documents.

Under BIR rules, all relevant supporting documents for a reinvestigation must generally be submitted within 60 days from filing the protest. Revenue Memorandum Order No. 26-2016 states that evaluation is based on documents submitted within that period and that further documents will not be accepted after its expiration. Failure to make the required submission can make the assessment final and executory. (Bir Cdn)

BIR guidance also provides that a protest is treated as a request for reconsideration unless it clearly indicates that reinvestigation is being requested. Reinvestigation is a remedy at the FLD/FAN protest stage; it is no longer available after issuance of an FDDA. (Bir Cdn)

The choice may also have consequences beyond document submission, including issues involving the running of collection periods. For a significant assessment, the remedy should therefore be selected only after reviewing the complete procedural history.

Step 4: Draft the protest issue by issue

Revenue Regulations No. 18-2013 requires the protest to state, among other matters:

whether it is a request for reconsideration or reinvestigation;
if reinvestigation is requested, the newly discovered or additional evidence intended to be presented;
the date of the assessment notice; and
the applicable law, rules, regulations, or jurisprudence supporting the protest. (Bir Cdn)

A well-prepared protest will normally go further and contain enough information for the BIR to understand exactly what is disputed.

For each assessment issue, identify:

the tax type and taxable period;
the amount assessed;
the BIR's factual finding;
the taxpayer's contrary facts;
the supporting documents;
the applicable statute, regulation, ruling, or jurisprudence;
any error in the BIR's computation; and
the precise relief requested.

Attach a schedule reconciling your position with the BIR's computation where useful.

Do not protest only the overall total while leaving individual adjustments unexplained. Under Revenue Regulations No. 18-2013, if an FLD/FAN contains several issues and the taxpayer disputes only some of them, the assessment attributable to the undisputed issues may become final, executory, and demandable. An issue inadequately supported by factual and legal grounds may likewise be exposed to finality. (Bir Cdn)

If you intend to contest every adjustment, make that unmistakable and address every adjustment separately.

Step 5: File the protest with the proper BIR office and keep proof

BIR Revenue Memorandum Circular No. 11-2014 directs taxpayers to file responses to the PAN and protests against the FLD/FAN with the duly authorized representative who signed the relevant assessment notice. Administrative requests for reconsideration elevated to the CIR from an adverse decision or inaction of an authorized representative are filed with the Office of the Commissioner. (Bir Cdn)

The assessment itself and any current BIR instructions should be reviewed for the exact filing office.

Do not assume that uploading documents through an unrelated BIR electronic service, emailing a revenue officer, or sending documents informally to an examiner constitutes a legally sufficient protest.

Whenever practicable, preserve:

a complete signed copy of the protest;
all annexes exactly as submitted;
the BIR receiving stamp showing the date of filing;
any official acknowledgment or tracking record;
a document index; and
proof of the authority of the person who signed or filed for the taxpayer.

If the BIR office refuses to receive a protest or gives conflicting filing instructions close to the deadline, obtain professional assistance immediately and document what occurred.

Current Friday filing rule for certain National Office requests

As of the source check for this article, BIR Revenue Memorandum Order No. 007-2026 generally places BIR personnel on a Monday-to-Thursday on-site schedule and Friday work-from-home arrangement, while requiring frontline services to remain operational on Fridays. (Bir Cdn)

BIR Revenue Memorandum Circular No. 35-2026 separately addresses, among other matters, a request for reconsideration of an FDDA filed with the National Office. When the deadline for that particular filing falls on a Friday during the applicable work arrangement, the circular provides for movement of the deadline to the next business day on which National Office personnel are working on-site. (Bir Cdn)

This should not be generalized into a rule that every BIR deadline falling on Friday is automatically extended.

Similarly, government work suspensions, typhoons, or other emergencies should not simply be assumed to extend a protest deadline. Check whether the BIR has issued an applicable circular or other authority covering the particular date, area, and filing.

Step 6: If you requested reinvestigation, complete the evidence within 60 days

The 60-day period is one of the most dangerous deadlines in the assessment process.

Prepare the supporting documents early. Depending on the issue, they may include:

tax returns and attachments;
audited financial statements;
general and subsidiary ledgers;
sales and purchase journals;
invoices and other source documents;
withholding-tax certificates;
contracts;
bank records;
importation documents;
proof of payment;
reconciliations;
schedules supporting deductions or tax credits;
corporate records;
correspondence; and
affidavits or other competent evidence where appropriate.

Submit the documents with a clear transmittal letter and index, and preserve proof that the complete set was received.

Under Revenue Regulations No. 18-2013, the special 60-day document-submission rule applies to reinvestigation, not to a request for reconsideration. (Bir Cdn)

Step 7: Calendar the BIR's 180-day period

After a valid protest, the next critical period is the BIR's 180-day period for action.

Under Revenue Regulations No. 18-2013:

for a request for reconsideration, the 180 days are generally counted from the filing of the protest; and
for a request for reinvestigation, the 180 days are generally counted from submission of the required supporting documents within the allowed period. (Bir Cdn)

If the appropriate BIR official does not act within the applicable 180 days, the taxpayer generally has two routes:

appeal the inaction to the CTA within 30 days after expiration of the 180-day period; or
continue waiting for the BIR's final decision, then appeal that decision within the applicable 30-day period after receipt.

Philippine tax jurisprudence recognizes the taxpayer's option to await the BIR's final decision rather than automatically losing the remedy upon expiration of the 180 days. The regulations emphasize, however, that the procedural choices are mutually exclusive once the taxpayer elects the route of appealing the inaction. (Judiciary eLibrary)

This is a stage where calendaring errors can be particularly serious. If you are contemplating an appeal based on BIR inaction, have the exact starting date and expiration date independently checked before filing.

Step 8: Read the FDDA carefully and identify who issued it

A decision on the protest is ordinarily communicated through a Final Decision on Disputed Assessment (FDDA). (Bir Cdn)

If the FDDA is issued by the CIR's duly authorized representative and is adverse in whole or in part, the taxpayer generally has 30 days from receipt to choose between:

appealing to the CTA; or
filing an administrative request for reconsideration with the CIR.

After an FDDA, a reinvestigation is no longer available as the administrative remedy under RMO No. 26-2016. (Bir Cdn)

If the CIR subsequently denies the administrative appeal, the taxpayer generally has 30 days from receipt of the CIR's decision to appeal to the CTA. Revenue Regulations No. 18-2013 specifically warns that filing another motion for reconsideration of the CIR's denial does not suspend the running of the period for CTA appeal. (Bir Cdn)

For safety, treat the CTA period as a strict statutory deadline. Do not assume that a later letter, follow-up request, informal meeting, or renewed motion with the BIR extends it.

When a CTA case becomes urgent

An appeal to the Court of Tax Appeals does not automatically suspend tax collection.

Under the CTA law, an appeal does not by itself stop payment, levy, distraint, or sale for satisfaction of the tax liability. The CTA may, however, suspend collection when it finds that collection may jeopardize the interests of the government or the taxpayer, subject to the conditions authorized by law, including a possible deposit or surety bond of not more than twice the amount claimed. (Judiciary eLibrary)

Seek tax-litigation assistance promptly if you receive, among other things:

a warrant of distraint or levy;
a garnishment notice;
notice of seizure or sale;
a collection letter asserting that the assessment is already delinquent;
demands directed to banks or third parties; or
other collection action while the assessment is still being disputed.

Do not assume that simply informing the collection officer that a CTA case has been filed stops enforcement.

The CTA has also adopted specific rules on electronic copies and electronic transmission of pleadings. Its recent En Banc resolutions address matters such as PDF copies, official email addresses, timing of electronic transmission, paper-copy requirements, and consequences of noncompliance. Anyone approaching a CTA deadline should verify the current CTA filing rules and resolutions instead of relying on an old filing practice or assuming that an ordinary email is sufficient. (Court of Tax Appeals)

Evidence to preserve throughout the dispute

Keep one complete chronological file containing at least:

Letter of Authority and related audit notices, if applicable;
Notice of Discrepancy and audit correspondence, where applicable;
PAN and PAN response;
FLD/FAN and all accompanying schedules;
FDDA and later BIR decisions or collection notices;
proof of receipt of every BIR communication;
copies of every submission to the BIR;
receiving stamps, registry receipts, courier records, and authorized electronic acknowledgments;
tax returns and supporting schedules;
accounting records and source documents relating to each disputed adjustment;
contracts and transaction records;
reconciliations and computations;
proof of partial or full payments, if any;
powers of attorney, board resolutions, or other authority documents where applicable; and
a written chronology showing every receipt date, filing date, and deadline.

Do not alter original documents or reconstruct evidence without identifying it as a reconstruction. If an important document is missing, document your efforts to obtain a legitimate replacement.

Common mistakes that can make a tax protest fail

A strong substantive defense can still be lost through procedure. Common mistakes include:

Treating a PAN reply as the protest against the FLD/FAN. The FLD/FAN has its own 30-day protest period.
Counting from the wrong date. The controlling date is commonly the date of receipt, so proof of service matters.
Filing a vague protest. The regulations require the nature of the protest and applicable factual and legal grounds.
Failing to contest every disputed adjustment. Unprotested issues may become final and demandable.
Calling the protest a reinvestigation but missing the 60-day evidence deadline.
Failing to say clearly that reinvestigation is requested. BIR guidance treats protests as reconsideration unless reinvestigation is clearly indicated.
Submitting important documents informally to the examiner without proving that they formed part of the official protest submission.
Filing with the wrong office or keeping no proof of timely filing.
Waiting for continued negotiations after a final CIR decision and allowing the CTA appeal period to expire.
Assuming a second motion for reconsideration stops the CTA deadline.
Assuming a CTA appeal automatically stops collection.
Assuming a holiday, storm, government suspension, Friday work arrangement, or office closure automatically extends every BIR deadline.

When professional help is particularly urgent

Consider obtaining advice immediately when:

fewer than several working days remain before a protest or appeal deadline;
the date or validity of service is disputed;
the assessment covers several years or tax types;
the amount is financially significant;
the BIR alleges fraud, falsification, deliberate nonreporting, or circumstances that could have criminal implications;
assessment or collection prescription may be an issue;
the dispute involves complex VAT, withholding, transfer-pricing, cross-border, related-party, or corporate-reorganization questions;
relevant accounting records are missing;
the BIR has begun garnishment, levy, distraint, or seizure proceedings;
the taxpayer intends to appeal BIR inaction after 180 days;
an FDDA or CIR decision has already been received; or
a CTA petition is being considered.

Tax assessment cases combine substantive tax law, accounting evidence, administrative procedure, and jurisdictional deadlines. Correct treatment often depends on the exact wording, signatory, date, and service history of the documents actually issued.

FAQ

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

Generally, no payment of the disputed assessment is required merely to file the administrative protest against the FLD/FAN.

A taxpayer may accept and pay an undisputed portion while protesting the remainder. BIR procedures contemplate payment of an accepted portion and continued resolution of the disputed portion. (Bir Cdn)

A later CTA appeal likewise does not mean that the taxpayer has automatically conceded the assessment, but the appeal itself does not automatically suspend collection.

Can I just write, “I disagree with the assessment”?

That is risky. Revenue Regulations No. 18-2013 requires specific information, including the nature of the protest and its applicable legal grounds. Each disputed issue should be supported by its factual and legal basis. (Bir Cdn)

Should I choose reconsideration or reinvestigation?

Choose reconsideration if the existing record is sufficient and you are asking the BIR to re-evaluate it. Choose reinvestigation if you need consideration of newly discovered or additional evidence. The latter carries the separate 60-day supporting-document deadline. (Bir Cdn)

Can I submit additional documents after the 60-day reinvestigation period?

Do not rely on being allowed to do so. RMO No. 26-2016 states that the reinvestigation is evaluated on documents submitted within the 60-day period and that no further documents will be accepted after the period expires. Failure to make the required submission can result in finality of the assessment. (Bir Cdn)

Does the BIR always have to issue a PAN first?

No. Section 228 and Revenue Regulations No. 18-2013 provide specific statutory exceptions in which an FLD/FAN may be issued without a PAN. (Bir Cdn)

What happens if the BIR does nothing for 180 days?

Depending on the stage and type of protest, the taxpayer may generally either appeal the BIR's inaction to the CTA within the applicable 30-day period after the 180 days expire or continue waiting for the final BIR decision and appeal after receiving it. The choice must be made carefully because procedural consequences attach once a route is elected. (Bir Cdn)

Can I appeal an FDDA issued by a BIR Regional Director or another authorized representative directly to the CTA?

Under the BIR regulations, an adverse FDDA from the CIR's duly authorized representative generally gives the taxpayer a 30-day period in which to choose between a CTA appeal and an administrative request for reconsideration elevated to the CIR. (Bir Cdn)

If the CIR denies my administrative appeal, can I file another motion for reconsideration to gain more time?

Do not rely on that approach. Revenue Regulations No. 18-2013 states that a motion for reconsideration of the CIR's denial does not toll the 30-day period for appeal to the CTA. (Bir Cdn)

Can I protest through eFPS, eBIRForms, or eAFS?

Do not assume those systems constitute an authorized channel for an assessment protest merely because they are BIR electronic services. Follow the filing instructions applicable to the assessment and the current BIR issuance governing the relevant office, and obtain reliable proof of filing.

What if the BIR sends a collection letter without a document labelled “FDDA”?

Do not ignore it. The legal effect of a communication depends on its substance, its context, the earlier protest, who issued it, and whether it demonstrates final action on the disputed assessment. BIR guidance itself recognizes circumstances in which a final demand for delinquent taxes may constitute a decision on a disputed assessment. (Bir Cdn)

Because a CTA deadline may be implicated, obtain advice promptly rather than waiting for a document with a particular title.

Official sources

General-information disclaimer

This article provides general Philippine legal and tax information and is not a substitute for advice based on the actual BIR notices, tax returns, accounting records, dates of receipt, and procedural history of a particular assessment. Tax remedies can turn on short statutory periods and case-specific questions involving service, authority, prescription, evidence, later BIR issuances, government work suspensions, and CTA procedure. If a deadline is approaching, obtain advice based on the original documents rather than relying solely on a general guide.

Sources and procedures last checked: August 23, 2026.