Tax Deposit in deceased's spouses number

Made 2017 estimated tax deposits in deceased spouses social security number, and filed 2017 1040 as single so deposits were not applied to clients account. Suggestions on how to get these payments applied to correct account?

File a tax return for the dead spouse.

What is the DOD of spouse? It was before 2017 and that is why your TP is filing single rather than MFJ with spouse in year of death? I suppose if you follow Frankly's suggestion, you would be filing a -0- tax return for the deceased spouse? (Might be weird if DOD was quite a while back...) But perhaps that might be the quickest way to get the refund so your TP can have the funds available to pay current taxes.

Spouse died in 2016, that's why his SS# on estimates. I was hoping I could avoid the underpayment penalties and the zero return .

Were the estimates sent in with only the deceased's SSN? Or were they joint with both SSNs?