What Is NC SIT Tax? Rate, Filing, and Form D-400

NC SIT tax is North Carolina’s state individual income tax, a flat 3.99% levy on taxable income for the 2026 tax year, down from 4.25% in 2025. It applies to residents on all income and to non-residents on income earned from North Carolina sources. Returns are filed on Form D-400 and are due April 15 each year, with the North Carolina Department of Revenue handling collection and administration.¹

The 2026 Rate

North Carolina uses a single flat rate instead of graduated brackets. For any tax year beginning after 2025, the rate is 3.99%.² That rate applies to every dollar of your North Carolina taxable income, whether you earn $30,000 or $3 million.

The rate has been dropping for several years. It was 4.99% in 2022 and has stepped down each year since.³ Additional reductions may kick in starting in 2027 if the state hits certain revenue triggers.

Who Has to File

Your obligation to file depends on your connection to North Carolina and how much you earned. A resident is anyone domiciled in North Carolina at any time during the tax year, or who lives in the state for more than a temporary purpose. Being physically present in North Carolina for more than 183 days creates a presumption of residency, though being absent more than 183 days does not automatically make you a non-resident.⁴

Residents report all income from every source. Non-residents report only income from North Carolina sources, such as wages from a job in the state, rental income from NC property, or profits from NC business operations. Part-year residents report everything earned while they were residents, plus any NC-source income earned during the non-resident portion of the year.⁵

You must file an NC return if your federal gross income exceeds the standard deduction for your filing status:

Single: $12,750
Married filing jointly: $25,500
Head of household: $19,125
Married filing separately: $12,750

These thresholds match the standard deduction amounts in the state tax code.⁶ Non-residents must meet the same thresholds and also have NC-source income before the filing requirement kicks in.

The deadline for calendar-year taxpayers is April 15. If that date falls on a weekend or holiday, it shifts to the next business day.¹

How North Carolina Taxable Income Differs from Federal

Your NC taxable income starts with the federal adjusted gross income from your federal return. The state then applies its own additions and subtractions before you take either the standard deduction or itemized deductions.

Standard Deduction

Most filers take the standard deduction, which cuts your adjusted gross income by a flat amount:

Single or married filing separately: $12,750
Head of household: $19,125
Married filing jointly or surviving spouse: $25,500

If you’re not eligible for the federal standard deduction, for example because your spouse itemizes on a separate return, your North Carolina standard deduction is zero.⁷

What Gets Added Back

North Carolina requires you to add certain income back to federal AGI that the federal government doesn’t tax. The most common addition is interest earned on bonds issued by other states or their local governments. The federal return excludes this interest, but North Carolina treats it as taxable.⁸

What You Can Subtract

North Carolina lets you subtract several types of income that were included in your federal AGI:

Social Security and Railroad Retirement Act benefits are fully subtracted. North Carolina does not tax them at all.⁷
Bailey Settlement retirement income: certain state, local, and federal government retirees who vested in their retirement plans before August 12, 1989, can subtract their entire pension or retirement benefits under the Bailey v. State court settlement.

Other retirement income and pension withdrawals that don’t qualify under Bailey are fully taxable. That catches many retirees off guard, especially those moving from states with broader retirement exclusions.

Itemizing in North Carolina

If your qualifying expenses exceed the standard deduction, you can itemize instead. North Carolina’s version is much narrower than the federal one. The state allows only two categories:

Charitable contributions, in the same amount you deduct federally.
Mortgage interest on a qualified residence plus real estate property taxes, with the combined total capped at $20,000. For married couples filing separately, the combined $20,000 cap applies across both spouses.

That is the full list. North Carolina does not allow itemized deductions for medical expenses, state and local income taxes, or most other federal itemized categories.⁷ The $20,000 cap is the detail most filers miss, particularly homeowners in higher-cost areas who assume their full federal deduction carries over.

Child Deduction

North Carolina offers a per-child deduction, not a credit, for each qualifying child who also qualifies you for the federal child tax credit. The amount phases down as your income rises, with the income brackets depending on filing status.⁹ The per-child deduction ranges from $3,000 at the lowest income tier down to $500 at the top of the phase-in range, then disappears at higher incomes. For married couples filing jointly, the phase-out finishes above $140,000; for single filers, above $70,000; for head of household, above $105,000.

Because this is a deduction, it reduces taxable income rather than directly reducing tax. At 3.99%, a $3,000 deduction per child saves about $120 in actual tax. Still worth claiming, but the real dollar impact is modest compared to the federal child tax credit.

Credit for Taxes Paid to Another State

If you’re an NC resident who also earned income in another state and paid income tax there, you can claim a credit to avoid double taxation on the same money. The credit equals the smaller of two amounts: the tax you actually paid to the other state on that income, or the North Carolina tax attributable to that income.¹⁰

You calculate this on Part 1 of Form D-400TC and attach it to your return along with the other state’s return and proof of tax paid. Report the net tax you actually paid after any refunds, not just the amount withheld. If you claim the credit and later receive a refund from the other state, you owe North Carolina back for the corresponding portion, plus penalties and interest.

The credit also applies to income taxes paid to foreign countries. It never covers taxes paid to cities, counties, or the federal government.

Filing Form D-400

North Carolina’s individual income tax return is Form D-400, available on the Department of Revenue website.¹¹ You’ll need your completed federal Form 1040, W-2s from all employers, any 1099 forms, and your Social Security number.

The form walks you through transferring your federal AGI, applying North Carolina additions and subtractions, choosing the standard or itemized deduction, and calculating the tax at 3.99%. If your employer withheld NC taxes, you subtract those withholdings to see whether you owe a balance or are due a refund.

The Department of Revenue partners with commercial tax software providers for electronic filing, which is the fastest route to processing.¹² You can also pay through the Department’s online eServices portal by bank draft or card.¹³ Paper returns can be mailed to the Department of Revenue in Raleigh, with the mailing address depending on whether you’re enclosing a payment.

Extensions

If you received a federal extension, North Carolina automatically grants you one too. You don’t need a separate state form unless you owe tax. If you do owe, submit Form D-410 with a payment by April 15, even though the extension gives you more time to complete the return.¹⁴ An extension delays the filing deadline, not the payment deadline.

Estimated Payments

If you have income not subject to withholding, such as self-employment earnings, rental income, or investment gains, you may need to make quarterly estimated payments. North Carolina requires them when you expect to owe $1,000 or more after subtracting withholdings and credits.¹⁵

Use Form NC-40, with quarterly due dates of April 15, June 15, and September 15 during the tax year, then January 15 of the following year. You can pay online or mail a check with the voucher. Falling short triggers an underpayment penalty, so it’s worth overestimating slightly if your income fluctuates.

Penalties for Late Filing or Late Payment

Missing the filing deadline and failing to pay on time are separate penalties that can stack:

Late filing: 5% of the net tax due for each month or partial month the return is late, up to a maximum of 25%.
Late payment: 5% of the unpaid tax if not paid by the original due date.

Both can apply to the same tax period if you file late with an unpaid balance.¹⁶ Interest also accrues on any unpaid balance from the original due date.

If you filed an extension and paid at least 90% of your total tax by April 15, the late payment penalty won’t apply as long as you pay the balance by the extended due date. If you paid less than 90%, the penalty applies to the full shortfall. Even if you can’t afford the bill, file on time. Doing so eliminates the 5%-per-month late filing penalty and limits the damage to just the flat 5% late payment charge.

Payment Plans

If you owe more than you can pay at once, the Department of Revenue offers installment agreements of up to 18 monthly payments. You can’t request one proactively. The Department first has to send you a Notice of Collection or final bill before you’re eligible to apply.¹⁷

To qualify, you must have filed all required returns, have no outstanding collection warrants or bank garnishments on the same tax periods, and allow the Department to draft payments directly from your bank account. If 18 months isn’t workable, you can request an exception by submitting Form RO-1062 with three months of bank statements to show financial hardship. While on a plan, you must keep filing and paying current-year taxes on time. A missed payment or new delinquency puts you in default.

How Long to Keep Records

North Carolina generally has three years from the later of the return’s due date or the date you filed to audit and propose an additional assessment.¹⁸ Keep W-2s, 1099s, receipts for deductions, and a copy of your filed return for at least three years.

One major exception: if you never file a return, or the state determines a return was fraudulent, there is no statute of limitations at all. The Department of Revenue can come back at any time. The practical takeaway is simple. Always file, even if you can’t pay the full balance, because filing itself starts the clock on how long the state can look back.

1
North Carolina Department of Revenue. Extensions
2
North Carolina Department of Revenue. Tax Rate Schedules
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North Carolina General Assembly. North Carolina Code 105-153.7 – Individual Income Tax Imposed
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North Carolina General Assembly. Session Law 2013-316
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North Carolina General Assembly. North Carolina Code 105-153.8 – Income Tax Returns
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North Carolina Department of Revenue. Individual Income Filing Requirements
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North Carolina General Assembly. North Carolina Code 105-153.5 – Modifications to Adjusted Gross Income
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North Carolina Department of Revenue. Interest Income
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North Carolina Department of Revenue. North Carolina Child Deduction
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North Carolina Department of Revenue. Credit for Income Tax Paid to Another State or Country
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North Carolina Department of Revenue. Individual Income Tax Forms and Instructions
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North Carolina Department of Revenue. eFile for Individuals
13
North Carolina Department of Revenue. eServices
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North Carolina Department of Revenue. Application for Extension for Filing Individual Income Tax Return D-410
15
North Carolina Department of Revenue. Estimated Income Tax
16
North Carolina Department of Revenue. Penalties and Fees Overview
17
North Carolina Department of Revenue. Installment Payment Agreements
18
North Carolina General Assembly. North Carolina Code 105-241.8 – Statute of Limitations for Assessments