April 30th
- Report income tax withholding and FICA taxes for first quarter 2018 (Form 941), and pay any tax due. (See exception below under “May 10th.”)
May 10th
- Report income tax withholding and FICA taxes for first quarter 2018 (Form 941), if you deposited on time and in full all of the associated taxes due.
June 15th
- If a calendar-year C corporation, pay the second installment of 2018 estimated income taxes.