do i owe a tax penalty if i paid 100% estimated taxes of last year's tax debt

[ottosensteve]

why is there a tax penalty if i paid estimated taxes equal to the taxes due last year

[baldietax]

did you pay them evenly each quarter?  if not, the penalty is assessed quarterly so you can meet the safe harbor total by year-end, but still end up underpaying in Q1, Q2 etc.

[SharonD007]

You can get hit with an underpayment penalty if you didn't pay the estimated quarterly taxes when they are due. Did you pay them by the due date?

You can contact the IRS to request a one-time abatement of your underpayment penalty. For individual tax returns, call 1-800-829-1040, 7 AM - 7 PM Monday through Friday local time.

For more information, refer to the TurboTax help article Guide to IRS Tax Penalties: How to Avoid or Reduce Them.

 Review ‌IRS topic 306, Penalty for underpayment of estimated tax for additional information. Also, review the TurboTax Help article Why am I getting an underpayment penalty?

[VolvoGirl]

You might be able to eliminate it or at least reduce it.  You can go to Federal Taxes tab or Personal tab, under Other Tax Situations and select Start by the Underpayment Penalties. You will answer a series of questions that may reduce or eliminate the penalty. Or you can elect to have the IRS figure the penalty for you.  It's form 2210.

It's under

Federal or Personal (for Home & Business Desktop)

Other Tax Situations

Additional Tax Payments

Underpayment Penalties - Click the Start or update button