The tax system is pay as you go, if you don’t pay estimated taxes, you can be assessed and under payment penalty even if you pay in full by April 15. The under payment penalty is about 1% per month which includes a penalty and interest. For a lump sum of income that you received in the fourth quarter of 20 20, the estimated payment is due by January 15, 2021. You can make a payment at www.irs.gov/payments. If you pay too much, you will get the excess back as part of your refund. Be sure to indicate on the estimated taxes paid page of TurboTax that you made the tax payment.
