Multi-State Tax Apportionment Calculator 2026 β Single Sales Factor
Calculate state income tax across 2-3 states using single sales factor and three-factor apportionment formulas. See apportioned income, state tax per state, and total multi-state burden.
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Net income before state apportionment State 1
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State 2
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Total Multi-State Tax
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State 1 Tax
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State 2 Tax
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Combined Effective Rate
Apportionment Detail
| State | Apportionment % | Apportioned Income | Tax Rate | State Tax |
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How Multi-State Tax Apportionment Works
When your business operates in multiple states, each state taxes only its portion of your income using an apportionment formula. The two most common formulas are:
Apportionment Formulas
Single Sales Factor (most states):
Apportionment % = State Sales / Total Sales
Three-Factor (equal weight):
Apportionment % = (Property % + Payroll % + Sales %) / 3
Three-Factor (double-weight sales):
Apportionment % = (Property % + Payroll % + 2 Γ Sales %) / 4
Apportioned Income = Total Income Γ Apportionment %
State Tax = Apportioned Income Γ State Corporate Rate
Key Rates (2026)
C-Corp rates: CA 8.84% | NY 7.25% (min) | IL 9.5% | PA 8.99% | NJ 9% | GA 5.75% | NC 2.5% | DE 8.7%
Pass-through top rates: CA 13.3% | NY 10.9% | NJ 10.75% | IL 4.95% | GA 5.75% | NC 4.5%
No corporate income tax: TX, FL (no personal income tax), WA, WY, NV, SD, AK
Pass-through top rates: CA 13.3% | NY 10.9% | NJ 10.75% | IL 4.95% | GA 5.75% | NC 4.5%
No corporate income tax: TX, FL (no personal income tax), WA, WY, NV, SD, AK
Extended
State Incorporation Comparison
Compare total tax burden of incorporating in Delaware, Wyoming, Nevada vs your primary operating state.
Compare total tax burden of incorporating in a low-tax state (Delaware, Wyoming, Nevada) vs a high-tax state like California or New York.
Incorporation State Comparison
| Incorporation State | Corp Tax Rate | Tax on $500K Income | vs California | Annual Savings |
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Note: Incorporating in a low-tax state does not eliminate tax in states where you have economic nexus. Physical presence creates nexus regardless of incorporation state.
Frequently Asked Questions
What is multi-state tax apportionment?
When a business operates in multiple states, it cannot simply pay full income tax to every state where it has activity β that would result in more than 100% of income being taxed. Instead, each state uses an apportionment formula to determine what percentage of the business's total income is attributable to that state. The most common modern approach is the single sales factor, where only the percentage of sales made to customers in that state is used.
What is the difference between single sales factor and three-factor apportionment?
Single sales factor (SSF): your apportionment percentage equals the percentage of your total revenue from customers in that state. Most states now use SSF to attract businesses by only taxing based on where customers are located, not where the business's assets or employees are. Three-factor apportionment uses an average of three ratios: property in state / total property, payroll in state / total payroll, and sales in state / total sales β either equally weighted or with sales double-weighted. States using three-factor include Massachusetts, Vermont, and others.
What is economic nexus and how does it affect apportionment?
Economic nexus means a state can tax your business income even if you have no physical presence there β just by having sufficient sales to customers in that state. Most states set thresholds of $100,000 in sales or 200 transactions. Once you have nexus, you must file a return and pay tax based on your apportioned income. Physical presence (office, employees, inventory) creates traditional nexus and typically results in higher apportioned income to that state across all factors.
Can I be taxed on more than 100% of my income across states?
In theory, the apportionment fractions should add up to 100% or less. However, "nowhere income" (income from states where you have no nexus) can result in income falling out of the formula. Some states have "throw-back" rules that capture sales to states where you have no nexus and throw them back to your home state β effectively taxing income that would otherwise go untaxed. "Throw-out" rules instead eliminate those sales from the denominator, increasing the apportionment fraction in the home state.
Which states use single sales factor apportionment?
Most major states have adopted single sales factor (or are moving toward it): California, Illinois, New York, Pennsylvania, Ohio, Michigan, Georgia, Virginia, Colorado, Washington, Oregon, and many others. A few states still use three-factor or modified apportionment: Massachusetts, Vermont, Alaska, Montana, and some others. States like Wyoming, Nevada, South Dakota, and Texas have no corporate income tax at all, making them attractive for incorporation.