Not that Lucky, Andy - I already checked and found out the business return was not extended (I should have mentioned that in my post). Thank you all for your quick responses.
Well if the sponsor and the plan have the same year end and the sponsor has an extension to file it's tax return, I believe that extends the 5500 due date (for up to 2.5 months). Obtain and keep a copy of the business extension. Check the 5500 instructions for the details.
You could be Lucky.
Do DFVCP now. The fee to file is small enough that it shouldn't even be a question. Admit the mistake to the client and explain that you are going to eat the costs since it was your mistake. Consider yourself lucky that you caught it before the client did, or worse yet, the IRS or DOL.
@BSI S125 The spouse can continue coverage through COBRA until the first of the following occurs:
The spouse exhausts the COBRA maximum coverage period (18 months of a termination of employment qualifying event); or
The spouse enrolls in Medicare (or another group health plan).
The spouse will want to enroll in Medicare upon becoming eligible to avoid a late enrollment penalty and the potential for the plan (COBRA) to assume Medicare primary coverage.
Full details here: https://www.theabdteam.com/blog/how-cobra-and-medicare-interact-for-retirees/
Note that in some scenarios the COBRA maximum coverage period for a spouse or dependent can extend beyond 18 months if the employee recently enrolled in Medicare prior to terminating employment. In that situation, the maximum coverage period for the spouse or dependent is the later of:
36 months from the date the employee enrolled in Medicare; or
18 months from the date of termination (or reduction in hours).
Full details on Slide 12 here: ABD Office Hours Webinar: Medicare for Employers.