Unfortunately, there is no workaround. As you mention if you include both contributions coded "D" for 2023 and "D22" retroactive contributions for tax year 2022. You get two error messages one stating 2 D codes cannot be entered and other that you over contributed for tax year 2023 which inaccurate. If you add them together and just use D code which is incorrect way to enter you get you over contributed for tax year 2023 .
I tried uploading PDF of my W-2 from my computer and got error message stating not connected to internet, which doesn't make any sense given that I have a download version of turbotax and the PDF was on my computer; furthermore, I was connected to internet. I also tried uploading W-2 with only one copy of W-2 on PDF, and no other information (i.e. my W-2 has copy 1 and copy 2 on same page and second page with explanation) and still got same error message. Tried to go to forms mode to see if there was a way to write in and there is not, and there is no method to include explanation statement to IRS or attach form 8275 (taxpayer disclosure statement which really is applicable to this situation) using turbotax. I spoke to a "tax specialist, supposedly CPA" at turbotax and they said since D22 applies to the prior tax year and does not affect 2023 tax lability leave it off the 2023 taxes and IRS will get a copy of the W-2 and will see which tax year the additional 401k or in my case TSP contribution went. Anyway I realize this is not the best answer; however, there is no method to enter this information other than if you submitted paper copies of your taxes which is not advisable. Sorry I cannot be more helpful.
