PS correction not counting towards annual addition?

I think I'm getting confused with how this works and tracking all the moving parts...

Calendar year 401k, SHNEC, PS plan for a partnership that we took over this year.  As we're reconciling it, we notice that the 2021 employer contributions were not deposited in 2022 - presumably they were deducted.

We've always taken the position that the SH has to be corrected so that has to be deposited ASAP with corrective earnings.  Fine, that's easy.

On PS... since the deposit was not made by 9/15/22, the deposit is subject to be counted in both the 2021 and 2022 annual addition limits.  But it wasn't deposited in 2022 at all... so there's no effect on 2022?  I assume this now becomes a SCP issue (it's small enough overall in the plan - we'll get to that in a minute)... and so even when they make the deposit now in 2023, it's under SCP and I don't see where that affects their annual additions limit (I just assumed it should, but most corrections don't).  So I must be missing something.  It must be somewhere that this would count towards the limit, otherwise any plan that missed the deposit deadline would just wait it out a couple of months and correct via SCP.

[Yes, the SH would also be in the same 'count towards annual additions' as the PS.  And, in fact, some of the partners' deferrals are in the same boat, too, so they've got late deferrals to add on top of this.]

So... I think it should be that all the missing 2021 deposits have to be made now, and they will offset either the 2022 or 2023 annual additions limit (their choice) by participant.  That feels right.  Nice to see that in black & white, though... or to have the actual right answer, either way.

Thanks.

Lots of moving parts here. In summary, SH NEC and PS contributions were allocated for 2021 PY, and presumably a corresponding 404 deduction was taken for 2021, but the contributions have yet to be made. At this point, the only way to correct the late contributions is under EPCRS. The corrective contributions plus interest will be made. Question is whether the correction would be an annual addition for 2021, 2022, or 2023 (the year of correction).

Under the 1.415(c) Regulations, if we assume that the employer's 2021 income taxes (with extensions) is due on October 15, 2022, then a contribution made by November 15, 2022 would relate to the 2021 limitation year. Likewise, a contribution made by November 15, 2023 would relate to the 2022 limitation year. There is no "double counting" of annual additions that I see in the 1.415 Treasury Regulations.

EPCRS, however, says that the correction is an annual addition for the limitation year to which the "corrective allocation relates"--2021 no matter when the correction is actually made.

Yes, EPCRS is giving you a freebie. But because you are correcting under EPCRS, its an annual addition for 2021.