Late profit sharing contribution

Odd situation - We did 2018 valuation and now when we get data for 2019 we find out that the sponsor did not actually deposit the full Profit Sharing contribution/deduction.  We could amend 5500 filing and tell him to amend tax return, but plan is aggregated with DB so this would cause serious problems.

If he makes up the money now (it was due by 09/15/19), how do we make that work? 

Is the amount of the dc contribution mandated by the plan document in some fashion or is the dc contribution amount entirely voluntary? 

My guess is that there will need to be a tax return/5500 amendment regardless, but there might be a way to fix any qualification issues through epcrs through additional allocations to NHCEs.

If the contribution goes in now, it will be considered 415 annual additions for 2020.

They will have to use the VCP for 415 failures.

I don't see a fix that will work without VCP.  IIRC, VCP corrective allocations to correct prior year errors are not subject to current year annual additions limitations.

It might not be a 415 failure.  Just annual additions for 2020.  It may curtail the 2020 employer contribution if there are those at or near the 415 limit.

By "serious problems", do you mean the DB/DC combination fails 401(a)(4) testing for 2018 without the contribution?  If so, there is still time to correct the failure under SCP.  As mentioned, a corrective allocation is treated as an annual addition for the year being corrected.  But, the deduction rules still apply based on the timing of the deposit.