What does the IRS letter tell you to do (besides pay up).?
It will be hard to contact a human at the IRS who can help you.
Meanwhile you can respond in writing that you want to amend.
If you attach the correct Form 8915-E to your letter, they may accept that.
OR they will tell you to file Form 1040-X + 8915-E.
Use your own best judgement.
IRS is way behind on paper correspondence and on Form 1040-X.
