Make a payment of your estimated tax for this year if you did not pay your income tax for the year through withholding (or did not pay in enough tax that way). Use Form 1040-ES. This is the final installment date for this year’s estimated tax. However, you do not have to make this payment if you file this year’s return (Form 1040) and pay any tax due by January 31 of the following year.
File your income tax return (Form 1040) for this year if you did not pay your last installment of estimated tax by January 15. Filing your return and paying any tax due by January 31 prevents any penalty for late payment of last installment.