What is a BIR Letter of Authority (LOA)?
A BIR Letter of Authority (LOA) is the official written authorization, signed by the Commissioner of Internal Revenue or a duly authorized representative, that empowers specifically named revenue officers to examine your books of accounts and records for a particular taxable year and tax type. It is the legal starting gun for any tax audit. Without a valid LOA, revenue officers have no power to inspect your records, and any assessment that results is void for lack of authority. This is the single most important document to understand if you have received a notice from the Bureau of Internal Revenue.
An LOA is not the same as a Letter Notice, a Notice of Discrepancy, or a tax mapping (Tax Compliance Verification Drive) visit. Those are separate tools. A true audit always begins with an LOA, today usually issued electronically as an electronic Letter of Authority (eLA). It must name the taxpayer, the taxable period, the tax types covered, and the assigned revenue officers by name. If officers other than those named try to examine you, the audit is legally defective.
How do I check if a BIR Letter of Authority is real?
Verify the LOA before you hand over a single document. As of 2026, the BIR launched an online LOA Verifier through its official chatbot "REVIE" under Revenue Memorandum Circular (RMC) No. 5-2026, letting you independently confirm that an LOA is authentic and recorded in BIR's system before you engage any examiner. The Assessment Service must issue an official validation response within three working days of a complete verification request.
This reform followed BIR's November 2025 suspension of audit operations (RMC No. 107-2025) to address fake LOAs, unauthorized audits, and inconsistent practices. When you receive an LOA, check five things: the taxpayer name and TIN, the taxable year, the tax types, the named revenue officers, and the dates. Confirm the officer presenting it matches the name on the document. If you suspect a fake LOA, do not surrender records and verify through REVIE first. If you have not yet registered or have informal records, our BIR registration guide and how to get a TIN guide explain the baseline you are expected to maintain.
What are the LOA validity and timeline rules?
An LOA is not open-ended. A revenue officer generally has 120 days from receipt of the LOA to complete the audit and submit a report. Historically, an unfinished audit required revalidation of the LOA, but since RMO No. 44-2010 (effective June 1, 2010) revalidation is no longer required even if the 120-day period lapses, and the Court of Tax Appeals has confirmed the LOA stays valid past 120 days; failure to finish on time instead exposes the revenue officer to administrative sanctions. For electronic LOAs, audit completion targets run to 180 days for Revenue District Office (RDO) cases and 240 days for Large Taxpayer cases (per RMC No. 82-2022).
Under Revenue Memorandum Order (RMO) No. 1-2026, the BIR is moving toward a single-instance audit framework, where a taxpayer generally receives one eLA per taxable year covering all internal revenue taxes, reducing the burden of multiple overlapping audits. The 2026 reforms also push system-generated, risk-based selection to reduce human intervention and strengthen due process.
What is the BIR audit process from PAN to FAN?
The audit follows a fixed sequence, and each stage has a hard deadline. Missing a deadline can make an otherwise winnable assessment final and collectible. Here is the flow under current rules (Revenue Regulations No. 22-2020 replaced the old Notice of Informal Conference with the Notice of Discrepancy).
| Stage | What it is | Your deadline |
|---|---|---|
| LOA / eLA | Authorization to audit a specific year and tax type | Verify before complying |
| Notice of Discrepancy (NOD) | Informal stage to explain findings | Discuss within 5 days; submit documents within 30 days of receipt |
| Preliminary Assessment Notice (PAN) | Proposed deficiency tax with facts and law | Reply within 15 days of receipt |
| Formal Letter of Demand / Final Assessment Notice (FLD/FAN) | Formal demand for payment | Protest within 30 days (non-extendible) |
| Final Decision on Disputed Assessment (FDDA) | BIR's decision on your protest | Appeal to Court of Tax Appeals within 30 days |
After you protest a FAN, if you request reinvestigation you have 60 days from filing the protest to submit supporting documents. The Commissioner then has 180 days to decide. If the BIR does not act within 180 days, you may appeal to the Court of Tax Appeals (CTA) within 30 days of the lapse, or wait for the FDDA and appeal within 30 days of receiving it.
Worked example: how a deficiency assessment escalates
Maria Santos runs a Cebu-based online store registered as self-employed under graduated rates. Her LOA covers 2024 income tax and percentage tax. The revenue officer cross-matches her declared gross sales of P1,800,000 against e-wallet and marketplace data showing P2,400,000 in collections, a P600,000 undeclared gap.
At the NOD, Maria shows that P250,000 of the difference was a refunded order batch and a personal transfer, supported by screenshots and bank records, leaving a P350,000 true underdeclaration. The BIR proposes deficiency income tax on the P350,000. Under graduated rates this falls largely in the 25% to 30% bracket, so the basic deficiency tax is roughly P87,500 to P105,000, before a 25% surcharge, 12% annual interest, and a compromise penalty. To pressure-test the income tax portion herself, Maria runs the figures through our income tax calculator and the percentage tax calculator so she can negotiate from a documented number rather than the officer's estimate. Because she responded at the NOD with documents, the assessable base dropped by P250,000 before it ever reached a FAN. This is why the early, informal stage matters most.
What triggers a BIR audit?
Audits are increasingly system-selected, but the same risk patterns repeatedly draw scrutiny. The most common triggers are underdeclared sales, expenses that look too large for the reported income, and mismatches between your VAT, income tax, and withholding tax filings.
- Declared sales that are lower than third-party data (marketplaces, banks, suppliers' alphalists, or Letter Notices).
- Reporting losses or very low income for several years while clearly operating.
- Discrepancies across your VAT, income tax, and withholding tax returns.
- Repeated late filing or non-filing, and failure to withhold taxes on payments.
- Unsupported or padded expenses without official receipts.
- Complaints from ex-employees, competitors, or other government agencies.
If you are an online seller, freelancer, or small business, reconciling your platform payouts to your declared sales before filing is the single best way to avoid a triggered audit.
What should I prepare when I receive an LOA?
Assemble organized, period-specific records before the first meeting; disorganized files invite findings. The standard BIR checklist requests your books of accounts (journals and ledgers), sales invoices and official receipts, purchase records, filed tax returns with proof of payment, withholding tax certificates (BIR Form 2307), bank statements, and audited financial statements where gross receipts exceed P3 million.
- Verify the LOA through REVIE and confirm the officer's identity.
- Note every deadline (NOD 5/30 days, PAN 15 days, FAN 30 days) on a calendar.
- Pull only the records for the covered year and tax types, nothing more.
- Reconcile your returns to your books and bank data before submitting anything.
- Engage your accountant or a tax lawyer before handing over documents.
- Keep an acknowledgment copy of everything you submit, with dates.
Common mistakes that turn a survivable audit into a costly one
Most taxpayers lose assessments on procedure, not on the underlying tax. These are the avoidable errors that competitors' guides rarely spell out:
- Treating the NOD as optional. The Notice of Discrepancy is your cheapest exit. Documents that knock down the base here save surcharge and interest later. Maria's example above cut P250,000 off the base at this stage.
- Filing a pro-forma protest. A FAN protest must state your arguments and legal basis. A bare "we disagree" letter is treated as no protest, and the assessment becomes final after 30 days.
- Choosing the wrong protest type. Use a request for reinvestigation when you still have documents to submit (it gives 60 extra days); use reconsideration when you are arguing on existing records and law.
- Surrendering everything immediately. Provide only what the LOA period and tax types require. Over-submission expands the audit's scope.
- Missing the 30-day CTA appeal. After an FDDA or the 180-day lapse, the CTA window is strict and jurisdictional. Miss it and you lose the right to contest, full stop.
How long can the BIR assess you? Prescription rules
The BIR generally has three years to assess, counted from the deadline to file the return or the actual filing date, whichever is later (Section 203, NIRC). Past three years, an assessment for that year has prescribed and is unenforceable. The major exception is Section 222: if you did not file a return, or filed a false or fraudulent return with intent to evade tax, the period extends to 10 years from discovery. The BIR must prove that a false return was deliberate to invoke the 10-year period; an honest mistake does not automatically extend it. Once a valid assessment becomes final, the BIR has another period (generally three years, or five years in the extraordinary cases) to collect by distraint, levy, or court action.
This is why filing on time and keeping clean records matters even when you owe nothing: it starts the three-year clock and limits how far back the BIR can reach. If you have unfiled years, understand the stakes first in our companion guide on what happens if you don't file taxes in the Philippines, then read our walkthroughs on how to file your ITR and quarterly tax deadlines to get current.
Your rights during a BIR audit
Due process is constitutionally protected, and the Supreme Court requires strict observance of the assessment notice rules. You have the right to a valid LOA naming the actual examining officers, the right to be informed in writing of the facts and law behind every finding (a PAN or FAN that omits these is void), the right to the full statutory periods to reply and protest, and the right to have your defenses genuinely considered, with reasons given if rejected. You also have the right to appeal to the independent Court of Tax Appeals. Knowing these rights, and the deadlines that protect them, is what converts a stressful audit into a manageable, winnable process.
Sources and References
The rates, thresholds, and rules on this page are drawn from official Philippine government issuances and reputable tax references. Tax rules change; always confirm current figures with the relevant agency before acting.
- RMC No. 5-2026: BIR introduces Online LOA Verification after audit suspension reform — Grant Thornton Philippines
- REVENUE MEMORANDUM CIRCULAR NO. 5-2026 (Digest) — Bureau of Internal Revenue
- Tax Alert No. 5 — Revenue Memorandum Order (RMO) No. 01-2026 (Single-Instance Audit Framework) — PwC Philippines
- Should LOAs Be Revalidated? (RMO 44-2010, 120-day rule) — Mata-Perez Tamayo & Francisco (MTF Counsel)
- RR No. 18-2013 — Due process in tax assessments (PAN 15 days, FAN 30 days, reinvestigation 60 days, 180-day rule) — 8Box Solutions
- Application of the BIR's 10-year prescriptive period (Sections 203 & 222, NIRC) — Deloitte Southeast Asia