Deduction of post termination funding

An employer is required to fund additional money due to market fluctuations to pay out the final benefits and close a plan. The date of the funding is past the  deduction deadline (9/15/20)  for the year of plan termination (2019).  Can they deduct the contribution for the year it is made even though the plan was not active for that year?  I am being told that it's not deductible for 2020 since they do not have a plan for 2020.  

Here are some example dates:

Plan termination date 12/30/19

Tax deadline 9/15/20.

Contribution date  11/1/20.

If the plan is not paid out until 2020 then they still have a plan in 2020 even if the plan termination date in the document is 12/31/2019.  

It is deductible.  If you don't believe me have an actuary prepare a formal 404(a) valuation.  

Thank you, I believe you.   I would not make sense to require a contribution and not allow it to be deductible.   My Actuary is who is telling me the contributions would not be deductible for the year they are made.