Amending a federal & state return from tax year 2018

[floridaflash1]

I received a CP2000 notification from the IRS in March 2020 for tax year 2018.  I had to pay additional taxes in 2020 due to a new tax ruling in 2019 that was retroactive to tax year 2018.  My question is do I need to file an amended return for 2018 and can I report the additional taxes I paid in March 2020 on my tax year 2020 Federal return? 

[xmasbaby0]

No you do not have to amend.   It sounds like the IRS changed something on your 2018 return and you already handled it by paying the additional tax owed.

I HAD TO PAY BACK TAX OWED 

The money you paid to the IRS for a previous year’s federal tax return is not deductible, so you do not enter it anywhere on your 2020 return.  If you paid taxes due in 2020 to your state or local government, you can enter that by going to Federal> Deductions and Credits> Estimates and Other Taxes Paid> Other Income Taxes.  You can enter the taxes you paid, but do not include any penalties or interest.

There are six states that allow you to enter the federal tax you paid on your state return--Alabama, Iowa. Louisiana, Missouri, Montana, and Oregon.  If you are filing in one of these states watch for the deduction when you prepare your state return.