BIR DAT File Naming Convention and Folder Structure: Avoiding eSubmission Upload Errors

The BIR does not publish one universal file-name string for every DAT filing type — naming conventions are documented per filing type, and the element enforced most consistently across all of them is the eSubmission email subject line, which must carry the form type, TIN, RDO code, registered name, and period covered. Getting the TIN format, branch code, or period tag wrong in that subject line — or in a filing type’s specific file-name pattern — is a common, avoidable reason a DAT submission gets flagged, delayed, or mismatched to the wrong filing.

This guide walks through what’s actually documented for RELIEF SLSP, SAWT, and Form 1604-C naming, how TIN and branch code should be formatted, and the mistakes that most often cause upload problems.

What actually needs a specific name — the DAT file or the email? #

Two separate things carry naming rules, and confusing them is itself a source of errors: the DAT file (or its zipped attachment) generated for a given filing, and the email subject line used to send it to esubmission@bir.gov.ph. The BIR’s own Alphalist Data Entry and Validation Module typically generates the DAT file’s internal name automatically when you export a validated file, so the part a filer controls by hand is usually the attachment’s file name (if renamed or zipped) and, always, the subject line of the submission email.

Confirming a file is clean before it’s ever named or sent still comes first — see How to Validate a BIR DAT File Before eSubmission for that step. Naming and packaging only matter once the file has already passed the Validation Module with zero errors.

How should the TIN and branch code be formatted in a file name? #

Every documented BIR DAT naming and subject-line convention breaks the Taxpayer Identification Number into two parts: the 9-digit base TIN and a separate 3-digit branch code, with no hyphens, spaces, or other separators inside either part. A TIN normally displayed as 123-456-789-000 becomes 123456789 with a branch code of 000 for the head office, or the actual 3-digit code assigned to a specific registered branch.

This TIN/branch-code split is the one formatting rule that shows up across every documented naming and subject-line pattern for DAT filings, whether the specific pattern is for a subject line, a file name, or both.

What naming conventions are actually documented, filing type by filing type? #

Rather than one master format, specific BIR DAT filing types have their own documented naming or subject-line patterns, sourced from BIR-adjacent workflows and tax practitioner guidance — mixing them up across filing types is itself a mistake worth avoiding. The table below lists what’s documented for three common filing types; treat these as the specific, sourced patterns for each type, not as interchangeable with one another.

Across all three, the recurring elements are the same: TIN (with branch code where applicable), the filing period, and the form or document type — the exact punctuation and field order is what changes filing type to filing type. If a source for QAP or annual alphalist naming that meets the same bar of verification becomes available, this table will be extended; until then, apply the same TIN/branch-code, RDO, and period discipline shown above to those filings even where a single quoted pattern isn’t available.

Worked example: naming a fictional Q2 2026 RELIEF SLSP submission #

Applying the documented RELIEF SLSP pattern to a fictional filer shows how the pieces combine — TIN and branch code first, then taxpayer name, period, and document type. Assume a fictional VAT-registered taxpayer, Luna Design Studio, with TIN 123-456-789-000 (head office, branch code 000), filing its Summary List of Sales for the second quarter of 2026.

Following the pattern documented by Respicio & Co. for SLSP:

• File/attachment name: SLSP_123456789-000_LunaDesignStudio_2Q2026_SLS_v1
• Email subject line: SLSP_123456789_2Q2026

If a correction has to be resubmitted later, only the version segment changes — v1 becomes v2 — while the TIN, period, and document type stay identical so the BIR can match the resubmission to the original filing. For what to do when that correction happens after the BIR has already acknowledged the original, see How to Correct and Resubmit a RELIEF, SAWT, or QAP DAT File After eSubmission.

What causes an “invalid file name” or mismatched-submission rejection? #

Most naming-related upload problems practitioners report trace back to a small set of avoidable mistakes, all involving the TIN, branch code, RDO, or period tag not matching what’s actually registered or actually inside the file. None of these are DAT content errors — they’re packaging errors, and they can hold up an otherwise clean, already-validated file.

• TIN with hyphens, spaces, or a merged branch code left in a file name or subject line instead of the raw 9-digit TIN and separate 3-digit branch code.
• Wrong or omitted branch code — using 000 for a taxpayer that actually filed under a specific registered branch, or leaving the branch code out entirely.
• RDO code in the subject line that doesn’t match the taxpayer’s actual Revenue District Office, which can happen after a taxpayer transfers RDOs but reuses an old email template.
• Period tag that doesn’t match the DAT file’s actual records — for example, a subject line labeled 2Q2026 attached to a file whose records are actually for the first quarter.
• An unzipped, oversized attachment when a filing period requires more than one DAT file (such as monthly files within a quarter) — zipping the set together keeps the files for one period as a single, clearly labeled package and keeps the email under size limits.

For a first-hand experience with the specific error types the DAT file’s own content produces on validation — as opposed to naming and packaging issues — see the filing-specific guides on RELIEF SLSP upload errors and SAWT DAT file errors.

Frequently Asked Questions #

Is there one official BIR file name format that covers every DAT filing type? #

No single published BIR document lays out one universal file-name string for every DAT filing type. What is consistently documented — by the BIR’s own eSubmission workflow and by tax practitioners who work with esubmission@bir.gov.ph — is that the email subject line must carry the form type, TIN, RDO code, registered name, and period covered, and that specific filing types (such as Form 1604-C and RELIEF SLSP) have their own documented naming patterns.

What TIN format does BIR eSubmission expect in a file name or subject line? #

The 9-digit Taxpayer Identification Number and the 3-digit branch code, with no hyphens or spaces — for example, a TIN normally written 123-456-789-000 becomes 123456789 with branch code 000 for a head office, or a distinct 3-digit code for a registered branch. Leaving the hyphens in, or merging the branch code into the 9-digit TIN, is a common cause of a rejected or mismatched submission.

Does the RELIEF SLSP DAT file have its own naming convention? #

Practitioner guidance documents a RELIEF SLSP naming pattern built from the TIN plus branch code, the registered taxpayer name, the period covered, and the document type (sales list or purchase list), and a matching email subject line in the form SLSP underscore TIN underscore quarter and year. This is separate from the SAWT and Form 1604-C conventions, which follow their own documented formats.

What causes an “invalid file name” or mismatched-file rejection on a DAT submission? #

The most commonly reported causes are a TIN entered with hyphens, spaces, or a merged branch code instead of raw digits; a branch code that doesn’t match what’s registered for that TIN; an RDO code in the subject line that doesn’t match the taxpayer’s actual RDO; and a return period tag that doesn’t match the period the DAT file’s records actually cover.

Should multiple DAT files be zipped into one folder before emailing to esubmission@bir.gov.ph? #

When a submission involves more than one DAT file — for example separate monthly files within a quarter — practitioner guidance recommends zipping them together before attaching, both to keep the submission under email size limits and to keep the set of files for one filing period together as a single, clearly labeled package.

Summary #

The BIR’s DAT eSubmission workflow does not run on one universal file-name format — it runs on a consistent set of identifying elements (TIN and branch code, RDO, registered name, and period covered) applied through filing-type-specific conventions, most reliably enforced through the email subject line. Format the TIN and branch code correctly, use the documented pattern for the specific filing type, double-check the RDO and period tags against what’s actually in the file, and zip multi-file submissions together. Naming only matters once the underlying file is already clean — start with What Is a BIR DAT File? and How to Validate a BIR DAT File Before eSubmission if that step hasn’t happened yet, and see How to Correct and Resubmit a DAT File After eSubmission if a naming or content error surfaces after the BIR has already acknowledged a filing.