Forfeitures in late correction of ACP failure

ACP test fails and we are now past the end of the following plan year - the statutory correction period. Therefore, sponsor is doing the one-for-one method via self correction. Correction method and plan document allow for forfeiture of non-vested match, but vested as of when - the end of the plan year to which the excess was attributable or as of the date of corrective distribution (for those vested)?

The vesting for those returns are as of the last day of the year being tested.  This is consistent with any other time.  For instance, the vesting computation period isn't always the plan year; it may be elapsed time.  Under this instance, you'd use vesting as of the last day of the plan year.  Why would it be any different?

Good Luck!

Thanks