October 11 — Employees who work for tips
If you received $20 or more in tips during September, report them to your employer - Details
October 14 — Everyone
Federal Holiday (Columbus Day) - Details
October 15 — Individuals
If you have an automatic 6-month extension to file your income tax return for 2018, file Form 1040 and pay any tax, interest, and penalties due - Details
October 15 — Corporations
File a 2018 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 Details
October 15 — Partnerships
Electing large partnerships: File a 2018 calendar year return (Form 1065-B). This due date applies only if you were given an additional 6-month extension - Details
October 15 — Social security, Medicare, and withheld income tax
If the monthly deposit rule applies, deposit the tax for payments in September.
October 31 — Certain small employers
Deposit any undeposited tax if your tax liability is $2,500 or more for 2018 but less than $2,500 for the third quarter.
October 31 — Federal unemployment tax
Deposit the tax owed through September if more than $500.
October 31 — Social security, Medicare, and withheld income tax.
File Form 941 for the third quarter of 2019. Deposit or pay any undeposited tax under the accuracy of deposit rules .If your tax liability is less than $2,500, you can pay it in full with a timely filed return. If you deposited the tax for the quarter timely, properly, and in full, you have until November 10 to file the return.