Key figures
Missouri accounting
2026, with sources
- Sourcing of services
- Market-basedSales other than tangible goods are sourced to where the customer benefits.
- Starting point
- Federal taxable incomeMissouri taxable income is built from federal taxable income, with state modifications.
- Federal income tax deduction
- 50%Corporations subtract 50% of the federal income tax they paid, on Part 3 of the MO-1120.
A low flat rate on a federal starting point
Missouri taxes C-corporations at a flat 4% of Missouri taxable income, a rate that has applied since 2020. The return is Form MO-1120, and the calculation starts from federal taxable income on Form 1120, then adds and subtracts Missouri’s own modifications. Because the starting point is federal, most federal changes — including how research spending under Section 174 is treated — flow into the Missouri number unless the legislature decouples from them. The Department of Revenue publishes each year’s legislative changes; check them before booking the state provision.
Missouri repealed its corporation franchise tax for tax years beginning after 2015, so there is no capital-based tax layered on top of the income tax.
Two Missouri-specific modifications
Missouri lets a corporation deduct half of the federal income tax it paid in computing Missouri income — unusual among states, and the reason the effective Missouri rate on a profitable company sits below the 4% headline. A loss-making startup paying no federal tax gets nothing from it.
Missouri has no net operating loss of its own. The Department’s instructions say the only NOL carried forward or back is the federal one, which reaches the MO-1120 through federal taxable income; a negative Missouri figure on the return is not an NOL. Missouri also limits a federal NOL carryback to two years, adding back any amount carried back further.
Single sales factor, market-sourced services
Since 2020 most multistate corporations apportion income to Missouri using a single sales factor. Sales of services and intangibles — which is how SaaS revenue is usually characterized for apportionment — are sourced to Missouri to the extent the customer receives the benefit in Missouri.
For the tax provision this means the Missouri rate that applies to a company depends on where its customers are, not where its office is. Book-tax differences in Missouri mostly mirror the federal ones, plus the state modifications on the MO-1120.
Deadlines
- 15th day of the 4th month after year endMissouri corporate income tax returnMO-1120
- 15th day of the 4th, 6th, 9th and 12th months of the tax yearEstimated tax payments, when Missouri tax is expected to be at least $250MO-1120ES
- Original due date of the MO-1120Payment of any tax expected to be owed, when filing on a federal extensionMO-7004
The federal baseline
This page covers what Missouri adds. The federal rules underneath it apply here too.
Common questions
Does a federal extension extend the Missouri return?
Yes, automatically, if the IRS has granted a federal extension: check the federal-extension box on the MO-1120 and attach a copy of Form 7004. The extension is to file, not to pay — any tax expected to be owed is paid by the original due date, with Form MO-7004. A corporation that has not filed and paid within 90 days of the due date (or the extended due date) can forfeit its Missouri charter.
Does Missouri still have a franchise tax?
No. Missouri’s corporation franchise tax was phased out and does not apply to tax years beginning after 2015. A Delaware C-corp qualified in Missouri pays the 4% income tax on its Missouri share of income and an annual registration fee to the Secretary of State, and that is the corporate-level cost.
If my team is in Missouri, is all my income taxed in Missouri?
Missouri apportions by sales alone and sources service and software revenue to where the customer receives the benefit. A SaaS company with a handful of Missouri employees but customers spread across the country will usually apportion only a small slice of its income here. A company selling mostly to Missouri customers apportions most of it, wherever its people sit.
Accounting next door
- IAIowa accountingIowa taxes corporations at 5.5% on the first $100,000 and 7.1% above for 2026, apportions by a single sales factor, and follows the federal code on a rolling basis.
- ILIllinois accountingIllinois taxes a C corporation’s income at 7% plus a 2.5% replacement tax, apportioned by a single sales factor and filed as a combined unitary group.
- KYKentucky accountingKentucky taxes corporations at 5% plus a limited liability entity tax with a $175 minimum, requires unitary combined returns, apportions on single sales factor, and decouples from bonus depreciation and Section 174A.
- TNTennessee accountingTennessee taxes corporations through a 6.5% excise tax on earnings and a 0.25% franchise tax on net worth, apportioned on a single sales factor from 2025, with the property measure repealed in 2024.
- ARArkansas accountingArkansas taxes corporate income on a graduated scale topping out at 4.3%, apportions by a single sales factor with market sourcing under Act 719, and allows no bonus depreciation.
- OKOklahoma accountingOklahoma taxes corporations at a flat 4%, apportions by three equal factors, repealed its franchise tax after 2023, and wants Form 512 30 days after the federal due date.
- KSKansas accountingKansas taxes corporations at 3.5% plus a 3% surtax above $50,000, and apportions by three factors until single sales factor arrives in 2027.
- NENebraska accountingNebraska taxes corporate income at a flat 4.55% for 2026, falling each year, with single-sales-factor apportionment, market sourcing and combined reporting.
Founder guides on this
- US GAAPUS GAAP for early-stage startups, in plain EnglishAccrual accounting, revenue recognition (ASC 606), leases (ASC 842), stock compensation and capitalized software: what each means for a small company.
- R&D taxThe R&D tax credit and Section 174A for startupsEngineering salaries can earn a federal R&D credit against payroll tax, and Section 174A lets you deduct US research again. What qualifies, what to track.
- FundraisingAudit-ready books before your Series AInvestors, lenders and auditors ask for the same things: accrual statements, reconciled accounts and support for every balance. How to be ready first.
More of the Missouri guide
- ReceivablesReceivables and sales tax in MissouriSales tax registration, economic nexus, whether SaaS is taxable, and collecting from customers
- PayablesPayables and contractors in MissouriPaying vendors and contractors: 1099 filing, use tax, contractor tests and withholding
- PayrollPayroll taxes and employer rules in MissouriWithholding, unemployment insurance, paid leave, minimum wage and the rules on paydays
- ComplianceCompliance and filings in MissouriRegistering to do business, annual reports, franchise tax and the filing calendar
- AdvisoryAdvisory: credits and decisions in MissouriCredits, incentives and the decisions that are cheaper to get right the first time
Sources
Checked against each agency’s own page on . Rates and thresholds change, usually on January 1.
General information for US companies, not tax, legal or accounting advice for yours. Rules and thresholds change; confirm the specifics with a CPA or the agency before you act on them.