SAFTCheck

SAFTCheck Field Notes

Practical guides on Portuguese SAF-T submission, ATCUD format, encoding pitfalls, and AT deadlines.

2026-05-11 · 6 min read

How to validate a SAF-T (PT) before submitting to AT

A pre-submission checklist: encoding, BOM, NIF, ATCUD, header dates, per-document date range, block totals, currency, and document status — what AT catches at intake and how to fix it before day 5.
2026-05-02 · 4 min read

How to fix the SAF-T UTF-8 encoding error in Portugal

Why AT silently rejects SAF-T XML files declared as UTF-8, and the one-line fix that makes them go through.
2026-04-09 · 3 min read

ATCUD format errors and how to fix them

The 8-character validation code, the dash, the sequence — what AT expects since 2023 and the patterns that fail.
2026-03-12 · 5 min read

SAF-T submission deadlines and AT rejection workflow

Monthly billing SAF-T due day 5, what changed in 2024-2026, when the QES mandate kicks in, and how to recover when AT rejects.

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