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 written administrative protest. The protest must be either a request for reconsideration based on the existing record or a request for reinvestigation based on newly discovered or additional evidence. Missing the 30-day period can make the assessment final, executory, and demandable. (Lawphil)
If you choose reinvestigation, submit all relevant supporting documents within 60 days from filing the protest. The BIR ordinarily has 180 days to act, reckoned differently depending on whether the protest is for reconsideration or reinvestigation. After an adverse final decision—or, in certain circumstances, after BIR inaction—the taxpayer generally has only 30 days to appeal to the Court of Tax Appeals (CTA).
These deadlines are unforgiving. Record the exact date each BIR notice was received, identify who received it, preserve the envelope or proof of service, and prepare the protest well before the last day.
First identify what BIR document you received
Not every BIR communication is protested in the same way. The document's title and procedural stage matter.
Notice of Discrepancy
During an audit, the BIR may first send a Notice of Discrepancy and invite the taxpayer to a discussion of the audit findings. This is an opportunity to explain discrepancies and submit records before the formal assessment process proceeds. BIR guidance states that if the taxpayer does not agree with the audit findings after the discussion, the case may be transmitted to the reviewing office for the issuance of deficiency-tax assessments under the applicable regulations.
Use this stage seriously. Correcting a factual misunderstanding before a PAN or FLD/FAN is issued can be considerably easier than litigating it later.
Preliminary Assessment Notice
A Preliminary Assessment Notice (PAN) ordinarily precedes the final assessment. It must show in detail the facts and the law, rules, regulations, or jurisprudence supporting the proposed assessment.
The taxpayer generally has 15 days from receipt of the PAN to respond. If no timely response is made, the taxpayer may be considered in default and the BIR may issue the FLD/FAN.
A PAN is not required in several situations specifically listed in Section 228 of the Tax Code, including certain mathematical errors apparent from the return, discrepancies between tax withheld and tax actually remitted, particular excess-credit carryover situations, unpaid excise tax, and certain transfers from exempt to non-exempt persons. In those cases, the BIR may proceed directly to an FLD/FAN. (Lawphil)
Because receipt of a PAN triggers a short response period, do not wait for the FLD/FAN before organizing your records.
Formal Letter of Demand and Final Assessment Notice
The FLD/FAN is the critical document for purposes of the Section 228 administrative protest.
Under Revenue Regulations No. 18-2013, the taxpayer, authorized representative, or tax agent may protest the FLD/FAN within 30 days from its receipt.
This is not merely a deadline for sending an informal objection. The protest must satisfy the regulatory requirements. A defective protest can be treated as having no force and effect.
Final Decision on Disputed Assessment
After considering the protest, the authorized BIR official may issue a Final Decision on Disputed Assessment (FDDA).
An adverse FDDA creates another important 30-day deadline. Depending on who issued the decision and the stage of the case, the taxpayer may have the choice of an administrative appeal to the Commissioner of Internal Revenue or a judicial appeal to the CTA.
The essential deadlines
| Stage | What the taxpayer generally must do | Deadline |
|---|---|---|
| PAN | Submit a response explaining disagreement with the proposed assessment | 15 days from receipt |
| FLD/FAN | File a valid administrative protest | 30 days from receipt |
| Reinvestigation | Submit relevant supporting documents | 60 days from filing the protest |
| Adverse FDDA of an authorized BIR representative | Appeal to the CTA or elevate the protest to the Commissioner, as applicable | 30 days from receipt |
| BIR inaction | Depending on the circumstances, appeal to the CTA after the 180-day period or wait for a final decision | CTA option generally must be exercised within 30 days after the 180-day period expires |
| Adverse decision of the Commissioner | Appeal to the CTA | 30 days from receipt |
The BIR's regulations distinguish the reckoning of the 180-day period. For a request for reconsideration, it runs from filing of the protest. For a request for reinvestigation, it runs from submission of the required supporting documents within the applicable 60-day period.
Do not calculate these periods casually. Weekends, holidays, the precise date and manner of service, the identity of the person served, and the procedural character of the BIR communication can matter.
Choose between reconsideration and reinvestigation carefully
A protest must identify whether it is a request for reconsideration or a request for reinvestigation.
Request for reconsideration
A reconsideration asks the BIR to reevaluate the assessment based on the existing records, without presenting newly discovered or additional evidence.
It can involve factual issues, legal issues, or both. The special 60-day document-submission period applicable to reinvestigation does not apply to reconsideration.
This may be suitable when the record already contains everything necessary and the dispute concerns matters such as:
- the BIR's interpretation of the Tax Code;
- application of a tax exemption or rate;
- computation errors;
- characterization of a transaction;
- treatment of deductions, withholding taxes, or credits already documented; or
- whether the assessment was issued within the applicable prescriptive period.
Request for reinvestigation
A reinvestigation asks for reevaluation based on newly discovered or additional evidence that the taxpayer intends to present.
The protest should identify that additional evidence, and all relevant supporting documents must generally be submitted within 60 days from filing the protest.
Do not call the protest a reinvestigation simply because the word sounds broader. The choice may also affect prescription. Section 223 of the Tax Code provides that a request for reinvestigation that is granted by the Commissioner can suspend the applicable prescriptive period for collection. The Supreme Court has continued to distinguish this from reconsideration, which does not have the same effect merely because it asks the BIR to review an assessment. (Lawphil)
Where prescription may determine the case, this choice deserves specific tax advice rather than boilerplate wording.
What a valid protest should contain
Revenue Regulations No. 18-2013 requires the protest to identify:
- the nature of the protest—reconsideration or reinvestigation;
- the date of the assessment notice;
- the applicable law, rules, regulations, or jurisprudence supporting the protest; and
- for reinvestigation, the newly discovered or additional evidence the taxpayer intends to present.
The protest should go further and address every contested assessment issue by issue.
For each item, explain:
- what the BIR alleged;
- the relevant facts;
- why those facts are inaccurate, incomplete, or legally insufficient;
- the applicable Tax Code provision, regulation, or controlling jurisprudence;
- the supporting documents; and
- the amount that should be cancelled or recomputed.
This is important because if an FLD/FAN contains several issues and the taxpayer contests only some of them, the assessment attributable to the undisputed issues may become final, executory, and demandable. The regulations likewise treat inadequately supported issues as undisputed in specified circumstances.
A one-paragraph letter saying only that the taxpayer "disagrees with the assessment" is risky.
Where and how to file the protest
BIR guidance directs the taxpayer to file the protest with the office of the Regional Director, Assistant Commissioner, or other authorized higher revenue official that issued the FLD/FAN, as applicable.
Revenue Memorandum Circular No. 39-2013 states that protest letters and requests for reconsideration or reinvestigation are to be filed by the taxpayer or duly authorized representative in person or through registered mail with return card with the appropriate issuing office. RMC No. 11-2014 similarly explains that the response or protest is filed with the duly authorized representative who signed the relevant PAN and FLD/FAN.
BIR's later published procedures likewise state that an administrative protest may be filed in person or through registered mail. When sent by registered mail, the post-office stamp on the envelope is treated as the filing date under that guidance.
For a deadline-sensitive protest:
- obtain a BIR-received copy if filing personally;
- if using registered mail, retain the registry receipt, tracking information, return card, and a complete copy of the envelope and filing;
- keep the entire signed protest and every attachment exactly as filed; and
- do not rely solely on an ordinary email unless the BIR has expressly provided an authorized filing mechanism applicable to your particular proceeding.
Build the protest around the actual assessment
Start with the FLD/FAN and prepare an assessment matrix. List each tax type, taxable period, issue, basic deficiency, surcharge or penalty, interest, and the factual basis stated by the BIR.
Then compare that with the original records.
Common matters worth checking include:
Whether the BIR stated the factual and legal basis
Section 228 requires taxpayers to be informed in writing of the law and facts on which the assessment is made. The implementing regulations similarly require the FLD/FAN to state its factual and legal basis. (Lawphil)
The Supreme Court has repeatedly treated these requirements as substantive due-process protections. In cases such as Commissioner of Internal Revenue v. Avon Products Manufacturing, Inc., the Court emphasized that the taxpayer must be adequately informed of how the BIR arrived at its assessment so the taxpayer can meaningfully defend against it. (Lawphil)
Do not assume, however, that every poorly drafted BIR letter automatically eliminates the tax liability. The validity of the assessment, the validity of a later FDDA, and the appropriate remedy can be separate questions.
Whether a required PAN was properly issued and served
Except for the statutory exceptions, a PAN is part of the due-process framework. Supreme Court decisions have treated failure to observe the PAN requirement as potentially fatal to the assessment. (Lawphil)
Check:
- whether a PAN was actually issued;
- when and where it was served;
- who received it;
- whether it described the factual and legal bases; and
- whether the taxpayer was given the prescribed opportunity to respond before the next stage.
Whether the assessment was issued on time
The general rule under Section 203 is that internal revenue taxes must be assessed within three years, subject to statutory rules on when the period begins and to exceptions.
Section 222 provides important exceptions, including a 10-year period after discovery in cases of a false or fraudulent return with intent to evade tax or failure to file a return. Written waivers and other statutory circumstances can also affect prescription. (eLibrary)
Prescription analysis can become complicated quickly. Review the tax-return filing date, assessment date, all waivers, extensions, and relevant BIR actions before asserting it.
Whether the computation matches the records
Reconcile the assessment against:
- filed tax returns and amended returns;
- audited or management financial statements;
- general ledger and subsidiary ledgers;
- invoices and other source documents;
- withholding-tax certificates;
- proof of tax payments;
- bank records where relevant;
- contracts;
- import or customs documents where relevant;
- schedules previously submitted during the audit; and
- BIR working papers or discrepancy schedules supplied to the taxpayer.
A protest is stronger when it does not merely say that the BIR is wrong but shows precisely where the computation diverges from the evidence.
Preserve evidence of receipt
Many tax disputes turn on dates.
Revenue Regulations No. 18-2013 recognizes personal, substituted, and mail service of assessment-related notices and also addresses service through professional couriers. Under specified circumstances, service upon an appointed tax agent or practitioner is deemed service upon the taxpayer.
Preserve:
- the original envelope;
- registry or courier tracking;
- acknowledgment receipts;
- the exact date stamped or written on the received copy;
- the identity and position of the person who received the notice;
- internal mailroom logs;
- emails or messages notifying management of receipt;
- the PAN, FLD/FAN, FDDA, and all attachments; and
- prior correspondence with the BIR.
Do not discard the envelope after scanning the assessment.
What happens after you file the protest
If the authorized BIR official denies it
If the protest is denied wholly or partly by the Commissioner's duly authorized representative, the taxpayer may generally choose within 30 days from receipt to:
- appeal to the Court of Tax Appeals; or
- elevate the protest through a request for reconsideration to the Commissioner of Internal Revenue.
At this administrative-appeal stage, RR No. 18-2013 does not allow another request for reinvestigation. The regulation limits the administrative appeal to reconsideration and to the issues addressed in the authorized representative's decision.
If the Commissioner denies the administrative appeal
An adverse decision of the Commissioner may be appealed to the CTA within 30 days from receipt.
A particularly dangerous trap is filing another motion for reconsideration with the Commissioner and assuming that this stops the CTA deadline. RR No. 18-2013 expressly provides that a motion for reconsideration of the Commissioner's denial does not toll the 30-day period for appeal to the CTA.
What if the BIR does nothing for 180 days?
BIR inaction does not necessarily mean that you have won.
When the applicable 180-day period expires without action, Section 228, the CTA Rules, and Supreme Court jurisprudence recognize an important choice.
The taxpayer may generally:
- appeal the BIR's inaction to the CTA within 30 days after expiration of the 180-day period; or
- wait for the BIR's final decision, and then appeal that final decision within 30 days from receipt. (Lawphil)
These options are mutually exclusive. Once the taxpayer invokes the CTA's jurisdiction on the basis of BIR inaction, the taxpayer cannot simultaneously proceed as though it had elected to wait indefinitely for an administrative decision. (Lawphil)
Calculate the 180-day starting point carefully. For reconsideration, RR No. 18-2013 reckons the period from filing of the protest. For reinvestigation, it is reckoned from submission of the required documents within the 60-day period.
Appealing to the Court of Tax Appeals
The CTA has jurisdiction over decisions of the Commissioner involving disputed BIR assessments and over qualifying inaction on those assessments. A taxpayer adversely affected by a decision, ruling, or qualifying inaction generally appeals by filing a petition for review with the CTA within 30 days from the applicable decision or expiration of the statutory period for action. (Lawphil)
CTA litigation is a court proceeding, not merely another letter to the BIR. The petition must comply with the Revised Rules of the CTA and current court requirements concerning pleadings, attachments, filing, docket fees, and electronic copies. The CTA maintains current filing guidance and electronic-submission information on its official website. (Court of Tax Appeals)
Because jurisdiction can turn on a missed filing period, taxpayers approaching the CTA stage should obtain tax-litigation advice before the administrative deadline expires, not afterward.
Does appealing to the CTA stop BIR collection?
Not automatically.
Republic Act No. 1125, as amended by Republic Act No. 9282, provides that an appeal to the CTA generally does not suspend payment, levy, distraint, or sale of property for satisfaction of the tax liability.
The CTA may, however, suspend collection when the statutory requirements are satisfied. The court may require a deposit or surety bond, subject to applicable law and jurisprudence. (Lawphil)
If the BIR has already issued a warrant of distraint or levy, garnishment, or another collection measure while a CTA case is being prepared or is pending, immediately examine whether a motion to suspend collection or other appropriate judicial relief is necessary.
Evidence worth preserving from the beginning
Keep a complete chronological audit file containing:
- the electronic Letter of Authority and amendments or replacements, if any;
- Notice of Discrepancy and schedules;
- PAN and attachments;
- response to the PAN;
- FLD/FAN and all computation schedules;
- proof of the date and manner each notice was received;
- protest letter and all attachments;
- proof of filing;
- additional evidence submitted for reinvestigation;
- FDDA;
- administrative appeal to the Commissioner, if one was filed;
- all BIR correspondence and meeting minutes;
- tax returns;
- accounting ledgers and reconciliation schedules;
- withholding certificates;
- invoices and contracts;
- payment confirmations;
- corporate authorization documents for representatives; and
- a deadline calendar showing the 15-, 30-, 60-, and 180-day periods.
The litigation record is much easier to defend when the taxpayer can prove exactly what was received, what was filed, when it was filed, and what evidence accompanied it.
Common mistakes that can make a strong tax defense fail
Waiting until the last day
A technically strong protest is useless if filed outside the statutory period.
Protesting the PAN but forgetting the FLD/FAN
A response to the PAN is important, but it does not substitute for the required protest against the FLD/FAN when the final assessment is subsequently issued.
Sending a vague objection
A letter saying "we disagree and request reconsideration" without satisfying the required contents may not constitute a valid protest.
Contesting only the total amount
Attack each assessment issue separately. An issue that is not properly disputed may become final even though other parts of the FLD/FAN remain contested.
Choosing reinvestigation but submitting the evidence late
If the protest relies on additional evidence, calendar the 60-day submission deadline immediately.
Filing with the wrong BIR office
The BIR has specifically warned taxpayers about filing protest letters with offices other than the proper office. Follow the issuing authority shown on the FLD/FAN and retain proof of proper filing. (BIR)
Ignoring an FDDA while continuing informal discussions
Informal meetings or settlement discussions should never be assumed to suspend a statutory CTA deadline.
Filing another motion with the Commissioner after a final CIR denial
A further motion for reconsideration does not toll the 30-day CTA period under RR No. 18-2013.
Assuming that a CTA appeal automatically stops collection
It does not. Suspension of collection generally requires appropriate relief from the CTA. (Lawphil)
When legal help is urgent
Seek tax counsel promptly when:
- fewer than several days remain before the 30-day FLD/FAN protest deadline;
- an FDDA or final CIR decision has already been received;
- the 180-day BIR inaction period has expired or is about to expire;
- the assessment is substantial enough that CTA litigation is realistically possible;
- the BIR alleges fraud or deliberate tax evasion;
- prescription depends on waivers, extensions, reinvestigation, or disputed service dates;
- the assessment involves several tax types or taxable periods;
- the BIR has issued a collection letter, warrant of distraint or levy, garnishment, or similar enforcement measure;
- the taxpayer believes the PAN, FLD/FAN, or FDDA violated statutory due-process requirements; or
- there is uncertainty over whether to choose reconsideration or reinvestigation.
A few days can determine whether the dispute will be resolved on its merits or lost on procedure.
Frequently asked questions
Do I have to pay the assessment before I can protest it?
Section 228 does not generally require payment of the disputed assessment as a condition for filing the administrative protest. Any undisputed portion, however, should be identified carefully because the regulations provide that assessments attributable to undisputed issues may become final and demandable.
Can I protest a PAN?
You should respond to a PAN within the prescribed 15-day period, but the statutory administrative protest discussed in Section 228 is directed against the subsequent FLD/FAN. If an FLD/FAN is later issued, file the required protest against it even if you already submitted a detailed PAN response.
Is an email enough to meet the 30-day protest deadline?
Do not assume so. Published BIR guidance specifically provides for filing with the proper BIR office in person or by registered mail. Unless an applicable current BIR issuance or written instruction expressly authorizes another filing method for your proceeding, use a recognized filing method and preserve incontrovertible proof of filing.
What if the BIR never sent me a PAN?
A PAN is ordinarily required, but Section 228 contains specific exceptions. If none applies, failure to comply with the PAN requirement can raise a serious due-process issue. Whether the assessment is ultimately void depends on the actual record, including service and the nature of the assessment.
What if I disagree with only one part of the FLD/FAN?
State expressly which other issues are also being disputed if you intend to contest them. Under RR No. 18-2013, an assessment attributable to an undisputed issue may become final, executory, and demandable even while another issue remains under protest.
What happens if BIR does not decide my protest within 180 days?
Depending on the precise procedural stage, you may generally appeal the inaction to the CTA within the following 30-day period or wait for the BIR's final decision and appeal that decision within 30 days from receipt. These remedies are alternatives, not parallel tracks. (Lawphil)
Does an FDDA with inadequate reasons automatically cancel the assessment?
Not necessarily. BIR regulations require an FDDA to state its factual and legal bases and identify itself as the final decision, but Supreme Court jurisprudence distinguishes the validity of the FDDA from the underlying assessment. A defective FDDA therefore requires case-specific analysis rather than an assumption that the entire tax assessment automatically disappears. (Lawphil)
Can BIR collection continue while my CTA case is pending?
An appeal to the CTA does not automatically suspend collection. The CTA has statutory authority to suspend collection in appropriate circumstances upon proper application and subject to the applicable requirements. (Lawphil)
Official sources
- National Internal Revenue Code, Section 228 — Protesting of Assessment: Republic Act No. 8424 on Lawphil
- Revenue Regulations No. 18-2013 — due-process and protest rules for deficiency assessments: BIR Revenue Regulations No. 18-2013
- BIR procedures explaining PAN, FLD/FAN, administrative protests, and CTA appeals: BIR Procedures in Responding to Deficiency Tax Assessments
- Revenue Memorandum Circular No. 39-2013 — filing and receipt of protest letters: BIR RMC No. 39-2013
- Revenue Memorandum Circular No. 11-2014 — clarification of assessment due-process procedures: BIR RMC No. 11-2014
- Republic Act No. 9282 — CTA jurisdiction, appeal periods, and effect of appeal: Republic Act No. 9282 on Lawphil
- Revised Rules of the Court of Tax Appeals: A.M. No. 05-11-07-CTA on Lawphil
- Current Court of Tax Appeals filing information and issuances: Court of Tax Appeals official website
Disclaimer
This article provides general information on Philippine tax-assessment protests and is not a substitute for legal or tax advice based on the taxpayer's actual FLD/FAN, audit record, taxable periods, service dates, evidence, and procedural history. Tax disputes are highly deadline-sensitive, and the correct remedy can change depending on the document received and the stage of the proceedings.
Sources and procedures checked as of August 25, 2026.