I got a tax notice saying I need to pay more money, even though i paid extra as part of my tax extension I filed. What should I do?

[VolvoGirl]

Did you enter the extension payment you made?   It should be on 1040 line 31 which comes from schedule 3 line 10.  Or what did the IRS say you missed?  Do you get Social Security?   A common reason is you didn’t enter the right taxable amount on 1040 or 1040SR line 6b?