October 15 – CorporationsFile a 2020 calendar year income tax return (Form 1120) and pay any tax, interest, and penalties due. This due date applies only if you timely requested an automatic 6-month extension by April 15.October 15 – Social Security, Medicare and withheld income tax
If the monthly deposit rule applies, deposit the tax for payments in September. October 15 – Nonpayroll Withholding If the monthly deposit rule applies, deposit the tax for payments in September.