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?
