Cash basis corporation has been deducting for many years pension contributions in the year paid instead of the year of the applicable compensation. For example, a March 2021 pension contribution applicable to 2020 compensation was deducted on the 2021 tax return and not the 2020 tax return. It is my understanding under IRC 404(a)(6) that if the pension contribution is based on 2020 compensation, then the payment is "deemed" to be made in the preceding year.
Assuming the deductions were in the wrong years, how is it corrected? On a Form 3115? What is the DCN?
Thanks.