Missouri follows federal tax deadlines, which makes things easier to remember. Personal income tax returns are due April 15th. If that date falls on a weekend or holiday, the deadline moves to the next business day.

Business deadlines depend on your entity type. S-corporations and partnerships file by March 15th, giving owners time to receive their K-1 forms before the personal filing deadline. C-corporations follow the April 15th deadline. Sole proprietors and single-member LLCs report business income on their personal return, so April 15th applies to them as well.

If you need more time, Missouri offers an automatic six-month extension when you file Form MO-60. But extensions only extend the filing deadline, not the payment deadline. You still owe interest on any unpaid taxes from the original due date. File for an extension and pay nothing, and you’ll face both penalties and interest when you finally settle up.

Estimated tax payments follow a quarterly schedule: April 15, June 15, September 15, and January 15 of the following year. Business owners and self-employed individuals who expect to owe more than $100 in state taxes need to make these payments. Miss them and you’ll face underpayment penalties even if you pay everything by April.

For sales tax filing, deadlines depend on your assigned frequency. Monthly filers are due by the 20th of the following month. Quarterly filers submit by the 20th of the month following the quarter. Annual filers have until January 20th for the prior year.

The businesses that struggle with tax deadlines are usually the ones with messy books. When your records are three months behind, tax season becomes a scramble to reconstruct the year instead of just filing the return. Working with bookkeepers who keep things current means your accountant gets clean numbers and you meet deadlines without the last-minute stress.