2018 Q3 tax calendar: Key deadlines for businesses and other employers

June 19, 2018
2018 QC tax calendar showing July, August and September

Here are some of the key tax-related deadlines affecting businesses and other employers during the third quarter of 2018. Keep in mind that this list isn’t all-inclusive, so there may be additional deadlines that apply to you. Contact us to ensure you’re meeting all applicable deadlines and to learn more about the filing requirements.  

July 31  

Report income tax withholding and FICA taxes for second quarter 2018 (Form 941), and pay any tax due. (See the exception below, under “August 10.”)

File a 2017 calendar-year retirement plan report (Form 5500 or Form 5500-EZ) or request an extension. 

August 10 

Report income tax withholding and FICA taxes for second quarter 2018 (Form 941), if you deposited on time and in full all of the associated taxes due. 

September

If a calendar-year C corporation, pay the third installment of 2018 estimated income taxes.

If a calendar-year S corporation or partnership that filed an automatic six-month extension:

  • File a 2017 income tax return (Form 1120S, Form 1065 or Form 1065-B) and pay any tax, interest and penalties due.
  • Make contributions for 2017 to certain employer-sponsored retirement plans. 

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