The enforce_period_start_day trigger and its sie-import pre-validation
rejected any non-first-of-month period_start whenever *any other* fiscal
period existed for the company. That blocked a real user flow: after
onboarding creates a default period (e.g. current year, day 1), importing
an SIE for an older förlängt första räkenskapsår (e.g. 2017-07-28 –
2018-12-31) failed with "Non-first fiscal period must start on the 1st
of a month".
Per BFL 3 kap., the chronologically first fiscal year is the one that
may be 6–18 months and start mid-month — which is a property of *when*
the period starts relative to others, not of insert order. The trigger
and pre-validation now allow mid-month start iff no existing period
starts earlier.
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Mattsson
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