A Bureau of Internal Revenue (BIR) Preliminary Assessment Notice can be alarming, especially when it lists large deficiency taxes, interest, surcharges, or alleged underdeclarations. A PAN is not yet the final assessment, but it is a critical opportunity to correct errors, present missing records, challenge unsupported findings, and preserve defenses before the BIR issues a Formal Letter of Demand and Final Assessment Notice. The most urgent rule is simple: respond in writing within 15 days from receipt of the PAN.

What Is a BIR Preliminary Assessment Notice?

A Preliminary Assessment Notice, commonly called a PAN, informs a taxpayer that the BIR proposes to assess additional taxes after an audit or investigation.

The PAN should identify:

The tax type involved, such as income tax, value-added tax, percentage tax, withholding tax, or documentary stamp tax
The taxable year or period covered
The alleged discrepancy
The proposed basic deficiency tax
Applicable surcharge, interest, and penalties
The facts and legal provisions supporting each finding

A PAN is generally preliminary rather than final. The technically correct response is therefore often called a reply or response to the PAN, although taxpayers and even BIR documents commonly refer to it as a protest.

An administrative protest in the strict legal sense is filed against the later Formal Letter of Demand and Final Assessment Notice, or FLD/FAN. A PAN response does not replace that separate 30-day protest if the BIR later issues a final assessment.

BIR document	What it means	Taxpayer’s usual deadline
Notice of Discrepancy or audit findings	Initial issues identified during the audit	Deadline stated in the notice
Preliminary Assessment Notice	Proposed deficiency assessment	15 days from receipt
FLD/FAN	Final administrative assessment and demand for payment	30 days from receipt to protest
Final Decision on Disputed Assessment	BIR decision on the FLD/FAN protest	Generally 30 days from receipt to appeal

Legal Basis for Responding to a PAN

The main legal basis is Section 228 of the National Internal Revenue Code of 1997, enacted through Republic Act No. 8424 and subsequently amended. It requires the BIR to notify the taxpayer of its findings and to inform the taxpayer in writing of the facts and law on which the assessment is based.

The detailed procedure appears in Revenue Regulations No. 18-2013, which amended Revenue Regulations No. 12-99. Under these regulations:

The PAN must show in detail the facts and legal authorities supporting the proposed assessment.
The taxpayer has 15 days from receipt to respond.
Failure to respond places the taxpayer in default at the PAN stage.
The BIR may then issue an FLD/FAN demanding payment of the proposed deficiency, including penalties.

The requirement to state the factual and legal bases is substantive, not merely technical. A taxpayer cannot prepare an effective response when the BIR provides only unexplained figures, generic statements, or broad citations unrelated to the specific transactions being questioned.

In Commissioner of Internal Revenue v. Unioil Corporation, the Supreme Court emphasized that the issuance and proper receipt of a PAN are integral parts of procedural due process. It also reiterated that a void assessment produces no valid tax liability for collection. (Supreme Court E-Library)

When the BIR may issue a final assessment without a PAN

Section 228 and RR No. 18-2013 allow the BIR to issue an FLD/FAN immediately, without first issuing a PAN, in limited cases:

The deficiency results from a mathematical error appearing on the face of the return.
There is a discrepancy between tax withheld and the amount actually remitted by the withholding agent.
A taxpayer claimed a refund or tax credit for excess creditable withholding tax but also carried over the same amount to a succeeding taxable period.
Excise tax on excisable articles was not paid.
Tax-exempt articles, equipment, vehicles, machinery, or similar property were transferred to non-exempt persons.

Outside these exceptions, the absence of a properly issued and served PAN may invalidate the succeeding assessment.

How to Count the 15-Day Deadline

The 15-day period generally begins on the day after actual receipt.

Under Article 13 of the Civil Code:

Exclude the date the PAN was received.
Count the following day as Day 1.
Include the 15th day. (LawPhil)

For example, if an authorized representative received the PAN on 3 August:

4 August is Day 1.
18 August is Day 15.

The period is counted in calendar days, not merely working days. When the last day falls on a regular holiday or special day, Section 28 of the Administrative Code of 1987 generally permits performance on the next business day. Because office closures and special holiday proclamations may vary, filing before the last regular working day is safer than relying on an extension. (LawPhil)

Preserve evidence of the receipt date, including:

The PAN envelope
Registry return card
Courier tracking record
Receiving stamp
Delivery receipt
Email transmitting the notice, if officially used
Internal log showing who received it and when

The date printed on the PAN is not necessarily the start of the deadline. The important date is normally the date of valid receipt.

How to Protest or Reply to a BIR PAN

1. Secure the complete PAN and all attachments

Check whether you received:

The PAN itself
Details of discrepancies
Computation sheets
Schedules for each tax type
Audit working papers or reconciliation schedules referred to in the PAN
A copy of the Letter of Authority, if not already available

Do not prepare the response using only the summary amount on the first page. A strong reply addresses each specific computation and assumption.

If a schedule mentioned in the PAN is missing, request it immediately in writing. Do not wait for the BIR to respond before beginning your own review.

2. Record the deadline and identify the proper BIR office

The response should ordinarily be filed with the office of the duly authorized BIR representative who signed the PAN. Revenue Memorandum Circular No. 11-2014 states that PAN responses and FLD/FAN protests should be submitted to the duly authorized representative who signed the relevant notice.

Depending on the audit, this may be:

A Revenue Regional Director
The Assistant Commissioner for the Large Taxpayers Service
Another duly authorized BIR official
The assessment or audit division identified in the notice

Addressing the reply only to the individual revenue officer who conducted the examination may be insufficient when the PAN directs filing with another office.

3. Create an issue-by-issue assessment matrix

Prepare a working table before drafting the response:

PAN issue	BIR’s factual basis	BIR’s legal basis	Taxpayer’s response	Supporting documents
Alleged undeclared sales	Third-party information exceeds VAT returns	VAT provisions cited in PAN	Difference represents loans and inter-branch transfers	Bank records, invoices, general ledger
Disallowed expenses	Missing withholding tax	Sections 34 and 57	Expense was not subject to withholding or tax was remitted	Contracts, withholding returns, proof of payment
Unreported compensation	Payroll variance	Withholding tax rules	Amount includes reimbursements and non-taxable benefits	Payroll register, receipts, policies

This prevents a common mistake: answering the assessment generally while leaving individual issues unaddressed.

4. Examine procedural defects as well as the tax computation

Check whether:

The PAN states specific facts, not merely conclusions.
The cited law actually applies to the transaction.
The PAN covers only the taxable year and tax types authorized for examination.
The notice was issued and signed by an authorized official.
The PAN was properly served.
The BIR gave the full 15-day opportunity to respond.
The proposed assessment was issued within the applicable prescriptive period.
The BIR’s calculations correctly apply payments, credits, carryovers, and prior adjustments.

A procedural objection should be stated clearly, but it is usually prudent to answer the underlying tax issues as well. Relying only on a procedural argument may leave the substantive assessment unrebutted if the BIR rejects that argument.

5. Gather the evidence that directly answers each finding

Useful supporting records may include:

Assessment issue	Common supporting documents
Alleged undeclared sales	Sales invoices, official receipts, VAT returns, audited financial statements, bank reconciliations, contracts
Disallowed purchases or expenses	Invoices, receipts, contracts, proof of payment, withholding tax certificates
Expanded withholding tax	BIR Forms 1601-EQ, 0619-E, 2307, alphalists, general ledger accounts
Withholding tax on compensation	Payroll records, BIR Forms 1601-C and 2316, employee classifications, benefit policies
VAT input tax	VAT invoices, import documents, proof of payment, subsidiary purchase books
Documentary stamp tax	Loan agreements, share issuances, debt instruments, proof of prior DST payment
Related-party charges	Intercompany agreements, transfer-pricing documentation, invoices, allocation schedules
Bank deposits treated as income	Loan documents, capital contribution records, inter-account transfer records, deposit reconciliation

Submit readable copies and retain the originals. Arrange the annexes in the same sequence as the issues discussed in the reply.

6. Draft a complete written response

A practical PAN response normally contains:

Taxpayer information State the registered name, Taxpayer Identification Number, address, taxable period, PAN date, and date of receipt.
Statement that the response is timely Identify the receipt date and the deadline.
General position State whether the taxpayer contests the entire proposed assessment or only specified portions.
Separate discussion for every issue For each proposed deficiency:
- Quote or summarize the BIR finding.
- Explain the relevant facts.
- Identify errors in the assumptions or computation.
- Cite the applicable Tax Code provision, regulation, or jurisprudence.
- Refer to specific annexes.
Corrected computation, when appropriate If part of the assessment is admitted, show the amount that should remain after correction.
Procedural objections Raise defects involving service, authority, insufficient factual or legal basis, prescription, or denial of the response period.
Specific request Ask the BIR to cancel or revise the proposed assessment and acknowledge the documents submitted.
Attachment index Number the annexes and describe each document.

A useful heading format is:

Re: Response to Preliminary Assessment Notice dated [date], received on [date], covering [tax type and taxable period]

The response should be signed by the taxpayer, an authorized corporate officer, or a properly authorized representative.

7. Attach proof of authority when someone else signs

For a corporation or other juridical entity, the BIR may require evidence that the signatory can act for the taxpayer, such as:

Secretary’s certificate
Board resolution
Special power of attorney
Written authority from the proprietor or partners
Accreditation or authorization documents of the tax agent

The PAN response itself is not ordinarily required to be notarized merely because it is a reply. However, affidavits, sworn explanations, special powers of attorney, and particular supporting instruments may require notarization.

For documents executed abroad, the BIR may require notarization and authentication appropriate to the country of execution. A public document from a country participating in the Apostille Convention is commonly authenticated through an apostille. Documents in another language should be accompanied by a reliable English translation when their contents are material to the assessment.

8. File the response and obtain indisputable proof

Personal filing is often the safest method because the taxpayer can obtain a stamped receiving copy showing:

Date and time received
Name or signature of the receiving officer
BIR office
Number of pages or annexes, when possible

Bring at least two complete copies: one for the BIR and one to be stamped for the taxpayer.

When personal filing is impracticable, confirm with the issuing office whether it will recognize submission by registered mail or accredited courier. Keep the registry receipt, tracking record, proof of delivery, and a complete copy of everything sent.

Do not assume that emailing the revenue officer alone constitutes valid filing unless the issuing office has expressly authorized electronic submission and confirms receipt.

9. Document all later meetings and submissions

After filing, the BIR may ask for:

Original documents for comparison
Additional reconciliation schedules
Clarification meetings
Sworn statements
Revised computations

After every conference, send a short written confirmation identifying what was discussed and what documents were submitted. Obtain stamped proof for supplemental filings.

The Supreme Court has held that the opportunity to submit evidence becomes meaningless if the BIR simply ignores the taxpayer’s explanations. In CIR v. Unioil Corporation, drawing from the Court’s discussion of the Avon assessment, the Court stressed that when the BIR rejects explanations and evidence, it must give a reasoned factual basis rather than merely repeat the same assessment figures. (Supreme Court E-Library)

What Happens After You File the PAN Response?

RR No. 18-2013 states that when the taxpayer disagrees with the PAN within the 15-day period, the BIR should issue the FLD/FAN within 15 days after the response.

However, RMC No. 11-2014 clarifies that an FLD/FAN issued after that 15-day period is not automatically invalid, provided it is issued within the legal period for assessment. The delayed issuance may be an internal administrative infraction by the responsible revenue officers, but it does not by itself cancel the assessment.

The possible outcomes are:

The BIR cancels the proposed assessment.
The BIR reduces some or all findings.
The BIR requests further documents.
The taxpayer pays an admitted amount.
The BIR issues an FLD/FAN maintaining or revising the assessment.

A PAN response does not stop the need to monitor later notices. Once an FLD/FAN is received, a new and stricter deadline applies.

How to Protest the FLD/FAN After the PAN

The FLD/FAN may be protested within 30 days from receipt through either:

Request for reconsideration — asks the BIR to reevaluate the assessment using the records already submitted.
Request for reinvestigation — relies on newly discovered or additional evidence that the taxpayer intends to present.

The protest must state:

Whether it is a reconsideration or reinvestigation
The date of the assessment
The specific facts and legal grounds for each disputed issue
The additional evidence intended to be submitted, when requesting reinvestigation

For a request for reinvestigation, relevant supporting documents must generally be submitted within 60 days from filing the protest. Issues not specifically disputed may become final, executory, and demandable.

If the BIR denies the protest, or fails to act within the applicable 180-day period, Court of Tax Appeals deadlines may begin to run. These periods require separate and careful monitoring; a motion for reconsideration filed with the Commissioner after a final denial does not necessarily suspend the period for appeal.

Procedural Problems That May Invalidate an Assessment

The PAN and FAN were issued too close together

The taxpayer must receive a genuine opportunity to answer the PAN before the BIR issues the final assessment.

In Commissioner of Internal Revenue v. Yumex Philippines Corporation, the Supreme Court addressed a situation in which the taxpayer received the PAN and FAN on the same day. The procedure deprived the taxpayer of the intended 15-day opportunity to respond to the proposed assessment. (LawPhil)

Similarly, in Prime Steel Mill, Incorporated v. Commissioner of Internal Revenue, the Court rejected supposed substantial compliance where the BIR issued the FLD/FAN without observing the taxpayer’s full PAN response period. (Supreme Court E-Library)

The PAN was delivered to an unauthorized person

A PAN personally delivered to a corporation should be received by the taxpayer or a duly authorized representative. Delivery to a building receptionist, temporary security guard, or unrelated person may be defective when there is no proof of authority to receive tax assessment notices.

In CIR v. Fort 1 Global City Center, Inc., the Supreme Court cancelled assessments after finding that BIR officers failed to establish the authority of the persons who received the PAN, FAN, and other notices. The Court stressed that actual participation in the protest process does not necessarily cure defective service. (Supreme Court E-Library)

Taxpayers must nevertheless keep their BIR registration address updated. As a rule, the address appearing in BIR records is presumed correct until the taxpayer properly reports a change. (Supreme Court E-Library)

The PAN does not explain the assessment

A PAN should do more than list amounts. It must explain the transactions, assumptions, computations, and legal provisions supporting the proposed deficiency.

A vague PAN may be challenged when it:

Uses unexplained lump-sum figures
Merely states “undeclared income” without identifying the transactions
Attaches schedules that do not reconcile with the proposed tax
Cites provisions unrelated to the finding
Fails to explain why the taxpayer’s prior reconciliation was rejected

The BIR used defective substituted service

Under RR No. 18-2013, the BIR may resort to substituted service when personal service is impracticable. Depending on the circumstances, the notice may be left with a clerk, a person in charge of the registered business address, or an adult residing at the taxpayer’s residence.

If nobody can be found, or the taxpayer refuses receipt, the regulation requires the participation of a barangay official and two disinterested witnesses, with the circumstances documented on the notice.

The 2026 Rules on Consolidated PANs

Under the BIR’s 2026 audit reforms, multiple electronic Letters of Authority covering the same taxable year may be consolidated under the Single-Instance Audit Framework.

Where cases are consolidated at the PAN stage, the BIR may issue a Consolidated PAN that expressly supersedes the earlier PAN or PANs. Revenue Memorandum Order No. 6-2026 provides that a fresh 15-day response period runs from receipt of the Consolidated PAN.

A taxpayer receiving a Consolidated PAN should therefore:

Confirm which earlier PANs were superseded.
Check that all tax types and taxable periods are accurately identified.
Recalculate the deadline from receipt of the new Consolidated PAN.
Restate relevant defenses even if they appeared in an earlier response.
Attach or incorporate earlier submissions clearly rather than assuming they remain part of the new record.

Common Mistakes When Responding to a PAN

Waiting for a meeting instead of filing a written response

A verbal discussion with the examiner does not substitute for a timely written response. File first and continue discussions afterward.

Sending a one-page general denial

Statements such as “we disagree with the findings” rarely resolve an assessment. Address each item and attach evidence.

Ignoring small or partially admitted issues

An undisputed issue can later become collectible. State clearly whether every issue is disputed, admitted, or subject to a corrected computation.

Submitting disorganized documents

A box of invoices without an index or reconciliation may not rebut the assessment. Connect each annex to a particular issue and amount.

Giving original records without an inventory

Present originals for inspection when necessary, but retain custody whenever possible. If originals must be left with the BIR, obtain a detailed acknowledgment identifying each document.

Assuming the PAN response protects against the FLD/FAN deadline

The PAN reply and FLD/FAN protest are separate filings. A taxpayer who answered the PAN can still lose the case administratively by failing to protest the FLD/FAN within 30 days.

Refusing to receive BIR notices

Refusal does not stop service. The BIR may use substituted service procedures involving a barangay official and witnesses. Accept the document, record the receipt date, and respond properly.

Frequently Asked Questions

Can I ignore a Preliminary Assessment Notice because it is not yet final?

Ignoring it is risky. Failure to respond within 15 days allows the BIR to treat the taxpayer as in default at the PAN stage and proceed with the FLD/FAN.

Can I ask the BIR for an extension of the 15-day PAN deadline?

The regulations do not establish a general right to an extension. A taxpayer may request accommodation, but should not rely on approval. File a substantive initial response within the original period and identify any supplemental records that will follow.

Does my PAN response need to be notarized?

A standard PAN response is not generally required to be notarized. Affidavits, special powers of attorney, sworn certifications, and certain supporting instruments may require notarization or authentication.

Where should I file the PAN protest?

File it with the office of the duly authorized BIR representative who signed or issued the PAN, following the filing directions stated in the notice. Obtain a stamped receiving copy.

Can the BIR issue an FLD/FAN even after I submit a strong response?

Yes. Filing a response does not guarantee cancellation. The BIR may accept, partly accept, or reject the taxpayer’s arguments. It should, however, consider the response and provide adequate factual and legal bases for the final assessment.

Can I appeal a PAN directly to the Court of Tax Appeals?

Ordinarily, no. The normal process is to respond to the PAN, protest the later FLD/FAN within 30 days, and appeal the BIR’s decision or qualifying inaction under the rules governing the Court of Tax Appeals.

What if the PAN was received by our receptionist or security guard?

Record exactly who received it and whether that person had authority to receive assessment notices. Defective service may be a valid due-process defense, especially for a corporation, but file a timely response while preserving the objection.

What if I received the PAN after moving to a new address?

Check whether the new address was formally registered with the BIR. Taxpayers are generally bound by the address in BIR records until they properly report the transfer. Preserve the envelope and delivery records and state any service objection in the response.

Should I pay the amount I agree with?

A taxpayer may pay an admitted amount, but the payment should be documented and properly applied to the correct tax type and period. The written response should clearly state that the remaining items are disputed and that the payment is not an admission of the balance.

What if the BIR never answers my PAN response?

Continue monitoring for an FLD/FAN. The BIR’s failure to issue it within 15 days after the response does not automatically invalidate a later assessment if it is still issued within the statutory assessment period.

Key Takeaways

A PAN is a proposed assessment, but it must be treated urgently.
File a written response within 15 days from valid receipt.
Address every finding separately and support each explanation with organized records.
Preserve procedural defenses involving inadequate factual or legal bases, defective service, lack of authority, prescription, or denial of the response period.
File with the office of the authorized BIR official who issued the PAN and obtain reliable proof of filing.
A PAN response does not replace the separate 30-day protest against an FLD/FAN.
When a Consolidated PAN is issued under the 2026 audit framework, a fresh 15-day response period generally runs from its receipt.