In 2008 I took advantage of the 2008 home buyer credit and received the full $7,500. I have filed my taxes using turbo tax since receiving this credit and have been paying it back since turbo tax said I needed to. 2020 I sold the home and turbo tax said I still owed $2500 which I paid with my taxes but the irs sent me a letter saying I still owe an additional $500. Did TurboTax calculate wrong or did the irs? I can’t find my old filings online that would verify I started paying this back and don’t owe any more.
You would have to know your past payment history. Possibly you can get an account transcript from the IRS if you did not save copies of your tax return.
You can also look up your FTHB account here.
In general, repayments of the 2008 credit would have started on the 2010 tax return, so after filing the 2019 return you would have paid 10 x $500, and owed just $2500. The IRS may have failed to credit one of your payments, but you will have to do some research to prove it.