Header dates: StartDate, EndDate, FiscalYear, DateCreated

What AT checks

The Header block of the SAF-T file describes the period the file covers and when it was generated. AT enforces a few invariants on these dates:

Field	Constraint
`StartDate`	The first date covered by the file.
`EndDate`	Must not be before `StartDate` (a one-day period is valid).
`FiscalYear`	The year of `StartDate`, or the year before it when the fiscal year doesn't follow the calendar year (e.g. February to January).
`DateCreated`	Should be on or after `EndDate`: you can't generate a file before the period it covers ends.

A correct example

The monthly invoicing file for September 2026, generated on 3 October by a company whose fiscal year is the calendar year:

<Header>
  ...
  <FiscalYear>2026</FiscalYear>
  <StartDate>2026-09-01</StartDate>
  <EndDate>2026-09-30</EndDate>
  ...
  <DateCreated>2026-10-03</DateCreated>
  ...
</Header>

All dates use the YYYY-MM-DD format. For a company whose fiscal year runs from April to March, the file for January 2027 would still say FiscalYear 2026, and SAFTCheck reports that as information rather than an error.

The header dates also set the period every document in the file must fall in: see documents outside the header period.

Sub-rules SAFTCheck applies

header.dates.range: fires when StartDate is after EndDate.
header.dates.fiscal_year_previous: FiscalYear is the year before StartDate's: correct for a non-calendar fiscal year, a mistake otherwise (info).
header.dates.fiscal_year_mismatch: FiscalYear is any other year (warning).
header.dates.created_before_end: fires when DateCreated < EndDate (warning; AT may still accept).
header.dates.future_end: fires when EndDate is in the future (warning).

Common mistakes

Year-end rollover. A January file with FiscalYear=2025 but StartDate=2026-01-01 from a company whose fiscal year is the calendar year. The ERP rolled the year on one field but not the other.
Wrong period unit. Submitting a quarter when AT expects a month, or the other way round. The dates declare the unit; mismatching it against the submission window is a separate AT-side check.
DateCreated set during testing. Files exported during ERP setup sometimes carry a DateCreated in the past or future from when they were actually built.

How to fix

Check the export period selection in the ERP: most issues come from selecting the wrong start/end month.
If the dates are right and only the FiscalYear is off, edit the company's fiscal year setting in the ERP and re-export. For one-off submissions, the inline editor can patch FiscalYear directly on the validation result page.
If DateCreated is in the future or before EndDate, fix the ERP system clock and re-export, or use the inline editor for the immediate file.

The combined header.dates.range finding (StartDate vs EndDate) is not editable as a single field: fix StartDate or EndDate individually with the inline editor, or re-export.

Inline editor: patch FiscalYear / EndDate / DateCreated in place.
Documents outside the header period
SAF-T (PT) submission deadline
SAF-T Portugal: what it is, who files, deadlines and rejections