Illinois Schedule NR-AP – Apportionment Detail for Nonresidents (2026)
Last reviewed: 2025-11-07
Use the Illinois Tax Form Calculator Schedule NR-AP: Apportionment Detail for Nonresidents as a stand alone tax form calculator to quickly calculate specific amounts for your 2026 Illinois state tax return. Alternatively, you can use one of our Combined Federal and State Tax Estimators to quickly calculate your salary, tax, and take-home pay.
Schedule NR-AP is used by nonresidents and part-year residents of Illinois to calculate the portion of income earned within the state. This schedule provides a detailed breakdown of income, deductions, and business apportionment factors that determine what share of total income is taxable by Illinois. The computed apportionment percentage feeds directly into Schedule NR and ultimately into Form IL-1040.
When to Use Schedule NR-AP
File Schedule NR-AP if you are:
- A nonresident who earned wages, self-employment, or business income in Illinois, or
- A part-year resident who lived in Illinois for part of the year and had income from both Illinois and other states.
This schedule is especially relevant for taxpayers with multi-state business operations or who receive income from Illinois partnerships, rental properties, or remote work sourced to Illinois.
How to Calculate Your Illinois Apportionment
- Determine your total income from all sources (Line 1).
- Determine your Illinois-source income (Line 2).
- Divide Line 2 by Line 1 to get your apportionment percentage (Line 3). This shows the share of income taxable by Illinois.
- Multiply your total adjusted gross income by the apportionment percentage to find Illinois taxable income (Line 4).
- Apply the Illinois flat rate of 4.95%. The result is your Illinois income tax due on apportioned income (Line 5).
Attach Schedule NR-AP to Schedule NR when filing as a nonresident or part-year resident.
| 1 | Total income from all sources | |
| 2 | Income earned in Illinois | |
| 3 | Apportionment percentage (Line 2 ÷ Line 1) | |
| 4 | Taxable income apportioned to Illinois (Line 1 × Line 3) | |
| 5 | Illinois tax due on apportioned income (4.95%) × Line 4 |
Understanding Illinois Income Sourcing
Illinois uses source-based apportionment for nonresidents. Wages are sourced to Illinois if services are performed within the state, even if your employer is based elsewhere. Business income is apportioned based on sales, property, and payroll factors within Illinois. For pass-through income, partnerships and S corporations calculate Illinois-source portions before issuing Schedule K-1-P or Schedule K-1-T to partners or beneficiaries.
Example
Example: You earned $120,000 total income in 2026, of which $30,000 was from Illinois. Divide $30,000 by $120,000 = 25%. Your Illinois taxable income is 25% of your total adjusted gross income. Multiply that by 4.95% to calculate Illinois tax owed on the apportioned share.
Why Schedule NR-AP Is Important
Nonresidents are only taxed on Illinois-source income, but without proper apportionment, the Illinois Department of Revenue may assume 100% of your income is taxable. Schedule NR-AP protects you by clearly documenting how much income should be subject to Illinois tax and ensures accurate credit calculations on Schedule CR if you pay tax to another state.
Tips for Accuracy
- Use accurate records of days worked in Illinois versus out of state if you are a remote employee.
- Include Illinois-source business income even if it was reported on federal Schedule C, E, or F.
- Keep W-2s and K-1s as evidence of Illinois earnings and withholding.
- Attach copies of other state returns when claiming reciprocal adjustments.
Last reviewed: 2025-11-07: If you believe this form requires an update, please contact us.
Related Forms and References
- Form IL-1040 – Individual Income Tax Return
- Schedule NR – Nonresident and Part-Year Resident
- Schedule CR – Credit for Tax Paid to Other States
- Schedule K-1-P – Partner’s Share of Income
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Frequently Asked Questions
Will IL tax my Roth conversions?
Conversions are taxable federally and typically flow to IL; IL retirement exclusion usually applies to distributions, not conversions—check IL guidance.
How do I amend my Illinois return?
File Form IL-1040-X after your original IL-1040 is processed; include revised schedules (e.g., Schedule ICR/CR/M) and explanations.
Why does Illinois distinguish pre-1969 and post-1969 gains?
Because Illinois enacted its income tax on August 1, 1969, any appreciation before that date occurred before the state had authority to tax income. Form IL-F preserves fairness by taxing only the gain realized since Illinois income tax law took effect. This approach avoids retroactive taxation while ensuring current gains are taxed appropriately.
When should Schedule FD be filed?
File Schedule FD with your annual IL-1040 return for the tax year in which the deferred income became federally taxable.
Why is Schedule M important for accurate Illinois taxes?
Illinois uses Schedule M to ensure fairness in applying its flat 4.95% tax rate. Because Illinois starts from federal AGI, this form ensures only Illinois-approved income is taxed and proper deductions are applied. It’s especially vital for retirees, military personnel, and taxpayers with multistate investments.
Important Notes
All calculations are estimates for guidance only. Always review your return and consider professional advice when submitting official filings.