Federal tax already paid on 1099-R. Why do I owe more

[Lisa995]

Taxes withheld from a 1099R distribution may not cover all the taxes due on it, when they withheld taxes the bank has no clue what tax bracket you may be in once the retirement income is added to the rest of your other income.

[Hal_Al]

You did not "already pay tax". What you paid was only withholding, an estimate of the tax and penalty 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.