Quote Originally Posted by Hoosier View Post
Since the s-corp has a valid extension, would this $9,000 SEP contribution be deductible on Line 17 of the 2016 form 1120-S for this cash-basis taxpayer?
Assuming you timely file the return and make the contribution on or before the extended due date, the answer is yes.

There are two revenue rulings for you to read. Rev Ruling 66-144 address the issue for accrual basis taxpayers.

That ruling was amplified by Rev Ruling 84-18. You need to read that ruling carefully as it primarily deals with IRAs but you will see as a result of ERISA, the holdings of RR 66-144 are extended to cash basis taxpayers.