Iran's fiscal year: the exact start and end dates

If you are reconciling an Iranian annual report, invoicing across the year boundary, or writing a date filter in a database, you need the actual Gregorian dates. The shorthand most sources give you is right about two years in three.

What defines it

The fiscal year is set in statute, not convention. Article 6 of Iran’s Public Accounting Act (قانون محاسبات عمومی کشور), approved 1 Shahrivar 1366 — 23 August 1987 — defines the financial year as one Hijri-Shamsi year beginning on the first day of Farvardin and ending on the last day of Esfand.

Article 155 of the Direct Taxation Act defines the tax year the same way, so for most entities the tax year and the fiscal year coincide. That article also allows for entities whose accounting period differs, so a specific company’s period is worth confirming rather than assuming.

Why “21 March to 20 March” fails

The Persian year begins at Nowruz, which tracks the spring equinox rather than a fixed Gregorian date. So the fiscal-year boundary moves with it.

Computed across Persian years 1390–1420:

A hardcoded 21 March start is therefore wrong in 38.7% of those years, and always in the same direction — the real year started a day earlier, so a filter keyed to 21 March silently drops the first day.

Widen the window and a third case appears:

Over two centuries the year begins on 22 March in 12 years. Any rule that allows only 20 or 21 March breaks on those.

The actual boundaries, recent and near-term

Note 1407: a common year that still begins on 20 March. Leap status and start date are related but not the same thing, so you cannot infer one from the other.

If you are writing code or a query

Three rules that will keep you correct:

1. Derive the boundary, do not store it. Convert 1 Farvardin of year N and 1 Farvardin of year N+1, then take the day before the latter as the end. That is right for every year including leap years.
2. Use a half-open range. start <= date < next_start avoids the off-by-one that a closed range invites when Esfand has 30 days.
3. Do not assume 365 days. A leap Persian year has 366, and the extra day is 30 Esfand — the last day of the fiscal year. 30 Esfand explained covers why it only sometimes exists.

The leap pattern is not four-yearly, which is what breaks most naive implementations: there is a five-year gap between the leap years 1403 and 1408. Persian leap years explained has the rule.

A note on sources

Several general references describe Iran’s fiscal year loosely, and at least one states it follows the Islamic (lunar) calendar. It does not — the statute says Hijri-Shamsi, the solar calendar. A lunar fiscal year would drift about eleven days earlier each Gregorian year, which is plainly not what Iranian annual reports show.

For the current Persian year, see what year is it in the Persian calendar.