@Xander1588
You can’t send form 5405, it is only used if you sold the house or stopped using it as your main home for some other reason.
The IRS is asking for form 5405 because they think your line 7b amount is incorrect, you paid more or less than they expected so they think you sold the house (or their computer thinks so, the letter is automatically generated). You need to send a letter explaining your situation, that you still live in the house and how you calculated the repayment amount, and the amount was correct.
