What's an efficient way to see all non-deductible traditional IRA contributions I have made? Is there a way to just do a search for 8606 on all past returns quickly?

[dmertz]

Because the basis in nondeductible traditional IRA contributions carries forward from one Form 8606 to the next one required to be filed, if all Forms 8606 were correctly filed your basis in nondeductible traditional IRA contributions carried into 2023 would be the amount on line 14 of your most recently filed Form 8606 for some year prior to 2023.

When examining old tax returns, they would normally be collated with the pages in the order of the sequence number in the top right of page 1 of each form or schedule.  Form 8606 has sequence number 48, so it should be present after lower sequence numbers and before higher sequence numbers if the pages are ordered properly.  If you have pdf files of your past tax returns, search them for "Sequence No. 48" to find the Form 8606 quickly.  You can also search for "Form 8606" but this might match in several places in your tax return.  Another option is to search for "your total basis in traditional IRAs" which is present on line 14 of Form 8606.

[Opus 17]

No.  The IRS states that you are required to keep copies of your own form 8606's for your entire life.  (This is an exception to the usual rule that tax forms can be discarded after 3 or 7 years.)  Your online transcript should go back 10 years, but you may want to log in and download your information now, before the 10th year gets erased and replaced with this year.

https://www.irs.gov/individuals/get-transcript

Your most recent form 8606 should have a running total of the after-tax basis in your traditional IRA, and should be the only form 8606 you need to file your current return.  However, if audited, the IRS does not have to allow any adjustment that you can prove, and even though you might have sent them the forms in the past, they don't have to (and probably can't) produce them for you, you have to prove it to them.  So you should get and keep copies of all your prior form 8606s.