I received a CP11 notice regarding my Year 2020 tax return and would like to submit a response expressing my disagreement with the assessment. Despite the notice stating I should call to review my account with a representative, I am unable to reach anyone at the IRS (it seems like a cruel joke to suggest calling when it's nearly impossible to reach a real person).
I also can't locate an address to mail my response. I'm afraid the address on the payment stub is only for payments, and I don't want my response to get lost in the shuffle.
Where should one mail a letter for this type of correspondence?