I received a 1099-INT for an account holding two municipal bonds (from the same state). Box 8 is showing the gross / total interest I received on these bonds, but there is nothing showing in other boxes (including box 13), even though I bought these bonds at a premium. Instead the amortization amount is just showing in the 1099 in the "Adjustments" section, under "Bond premium - Tax-exempt obligations (noncovered lots)", but it says it's not reported to the IRS. In years past, I believe I've included this bond premium amortization on what I've reported on my tax returns. How should I account for this? Can I just manually input this amount into Box 13 (even though it's not reported on the 1099 I received this way)?
Yes, you go ahead and report it yourself. Try to keep records of your original purchase as a back-up.
Their statement was just that they will not be reporting it. That doesn't mean that you can't.
____________________________
Why would they do this. 1) for older purchased bonds, they are not "required" to report it, and may not want to be responsible for reporting it (for some reason) 2) IF older purchased bonds were transferred from one broker to another at some date some years ago, they may not have the actual purchase price/premium you paid.