I paid the taxes when I withdrew my retirement but forgot to enter it on my taxes ... how do I fix this

[nmcdow3]

When I filed in 2018 I forgot to enter the retirement I had withdrawn on my return. I need help fixing this now. I paid the taxes on it when I withdrew the money and now they want to tax it more.

[Critter-3]

Read that CP2000 closely ... did they give you credit for the withholding already ?   If so they are correct so pay the bill. 

If you want to use the amendment process to double check and see how they are correct ...

See this TurboTax FAQ for help with amending.

[Hal_Al]

You did not "already pay tax". What you paid was only withholding, an estimate of the tax  due. No piece of income is taxed individually. All your income, including pension plan distributions, is added together at tax filing time. The tax is calculated on that total (after adjustments, deductions, exemptions and credits). Then withholding is subtracted to determine if you owe more or get a refund.

As the other  answer said, check the IRS notice to see if they gave you credit for the withholding (box 4 of the 2018 form 1099-R).

The IRS calculations are not always correct. Recalculating your tax  to confirm the IRS billing is recommended. If you come up with something different, you should submit an amended return.