They are beyond the time period to deposit annual additions for the 2015 year, so the only way a 2015 contribution can be done now is under EPCRS. The SH contribution is required, so it definitely needs to be corrected. If it isn't corrected, the plan is disqualified. If the PS contribution was discretionary, I don't know if it can be corrected. Rev. Proc. 2016-51, Section 6.02(4)(b) says that corrective deposits are considered annual additions for the year being corrected, but the normal rules under Section 404 regarding deductions apply. With a correction being made now, I read that as you would allocate for 2015, but deduct in 2017. I'm not a tax person, but I would agree with you that they should not have deducted it for 2015 when it wasn't deposited.