BIR Tax Audit in the Philippines: The Letter of Authority (LOA), PAN/FAN Assessments and How to Respond

An Audit Starts With a Letter of Authority (LOA) — Check It First

In the Philippines, a formal tax audit typically begins with a Letter of Authority (LOA). Issued by the BIR (the tax authority), it authorizes specific examiners to audit specific tax types for specific taxable years. In other words, receiving an LOA is what marks the start of a formal audit, and it defines the boundaries of that examination.

So the first thing to do on receiving a notice is not to rush documents over, but to verify the LOA itself: Is it valid? Are the named examiners the ones actually at your door? Do the tax types and years covered match what is being requested from you? Requests beyond that scope deserve careful scrutiny. In practice, an LOA's validity and scope are an important basis in any later protest, so keep the document safe and check it thoroughly from the outset. If you are unsure, have the Yixing compliance team review it early.

The Full Map of a BIR Tax Audit

Understanding the whole process is what keeps you from panicking at any single step. A Philippine BIR tax audit generally runs along this chain:

• 1. LOA issued: authorizes specific examiners for specific tax types/years, formally opening the audit.
• 2. Submit books and vouchers: the taxpayer submits statutory books, invoices, contracts and other support per the request list.
• 3. Audit findings: examiners review the records and form preliminary discrepancies and findings.
• 4. Preliminary Assessment Notice (PAN): the BIR issues a preliminary assessment of the discrepancies found.
• 5. Formal Assessment Notice / Formal Letter of Demand (FAN/FLD): the assessment amount is formally determined and demanded.
• 6. Written protest: the taxpayer may file a written protest within the statutory period, supplementing evidence.
• 7. Appeal to the CTA: if the dispute remains unresolved, it may be appealed to the Court of Tax Appeals (CTA).

Each link maps to a document and a deadline. With this map in mind, any notice tells you where you stand and what to do next. It rests on the same underlying logic as your day-to-day tax compliance rhythm: whether your records hold up to review decides how smoothly the audit goes.

Reading the PAN and the FAN/FLD: Two Notices That Carry Weight

The two most important documents in the process are the Preliminary Assessment Notice (PAN) and the Formal Assessment Notice / Formal Letter of Demand (FAN/FLD).

The PAN is the BIR's preliminary assessment of the discrepancies found, usually setting out the basis for its position. It gives the taxpayer a window to respond, explain and submit evidence before anything is finalized. Do not treat a PAN as an ignorable draft: your response to it often shapes whether the matter proceeds to a formal assessment.

The FAN/FLD is the notice that formally determines the assessment amount and demands payment. By this stage the matter has been formally characterized, and a taxpayer who disagrees must move into the written protest procedure. The two notices differ in name, content and stage; being able to read them and know which step you are on directly determines your response strategy. Exact amounts, computations and bases are governed by the notice text and the BIR's prevailing rules, and are best worked out case by case by a professional tax agent.

The Written Protest and Its Deadline: Miss It and You Waive Your Rights

If you disagree with the assessment, the law gives you a remedy: the written protest. This is the taxpayer's formal channel to object, submit supplementary evidence and ask for reconsideration.

But there is a line you cannot cross: the deadline. A protest must be filed within the statutory period, and filing late is generally treated as a waiver of your rights; the assessment then becomes final and the remedy window closes. This is the point in an audit most often lost to delay, not on the merits, but on missing the period. So on receiving any notice, record the corresponding response deadline immediately and work backward to plan your preparation, rather than moving only as the cutoff nears.

The persuasiveness of a protest ultimately rests on whether your records are complete, consistent and traceable. That is the same foundation the Yixing compliance service maintains in your statutory books year-round: solid records give a protest its footing.

Still Disagree? Appeal to the Court of Tax Appeals (CTA)

If the dispute remains unresolved after the written protest, the taxpayer has a further remedy: an appeal to the Court of Tax Appeals (CTA). The CTA is a judicial body dedicated to tax disputes, moving the matter from the administrative level into judicial review.

By the time you reach the CTA, the procedure is more formal and demanding, usually requiring coordinated professional tax and legal teams, and it carries its own strict deadlines and procedural requirements. For most companies, the more practical goal is to resolve the matter in the earlier steps, doing the LOA check, document submission, PAN/FAN responses and written protest thoroughly so the dispute never escalates to litigation. That said, where an appeal is genuinely warranted, exercising the right promptly and by the book is equally a legitimate protection for the taxpayer.

What Triggers an Audit, and How to Prevent It Early

Audits are not entirely random. Common triggers include anomalies in filed data, deviation from industry benchmarks, recurring reported losses, and mismatches against third-party data (for example, your filings not reconciling with data from customers, suppliers or other government systems). These signals raise the odds of being selected for audit.

It follows that the best response happens before any LOA arrives: keep your books clean, file accurately and on time, keep each period's data consistent and able to withstand cross-matching, and you head off the risk. That is exactly the value of an ongoing compliance calendar. In addition, if your ownership or operations involve foreign capital and local nominee arrangements, mind your Anti-Dummy compliance so that structural weaknesses are not surfaced during an audit.

Rather than scrambling once you are audited, let the Yixing compliance team watch the whole chain from bookkeeping and filing to record retention, keeping audit risk low, so that if an LOA does arrive, you are prepared and unshaken.