Connecticut Form CT-W4NA: Nonresident Withholding and Work Percentage

Connecticut Form CT-W4NA is the certificate a nonresident employee gives their Connecticut employer to show what percentage of their wages should actually be subject to Connecticut income tax withholding. If you live in another state but spend some workdays in Connecticut, this form is what keeps your paycheck from being taxed as if every day were a Connecticut day. Skip it, and your employer is required by law to withhold Connecticut tax on 100% of your wages.¹

Who Should File It

Any nonresident employee who splits working time between Connecticut and another state should file this form with their employer. Connecticut requires every employer with an office or business in the state to withhold income tax from wages paid for services performed there, whether the employee lives in Connecticut or not.² The CT-W4NA is what tells payroll to withhold only on your Connecticut share.

There is a threshold worth checking first. If you expect to work in Connecticut for 15 days or fewer during the calendar year, that compensation is not treated as Connecticut-sourced and no withholding is required. But it’s all-or-nothing. Cross the 15-day line and your employer must withhold on all Connecticut-sourced compensation, including the pay for those first 15 days.¹ If your travel schedule looks borderline, track your days from January.

Calculating Your Connecticut Work Percentage

The whole form comes down to one number: the percentage of your workdays you expect to spend in Connecticut during the year. Divide your expected Connecticut workdays by your total expected workdays. Total workdays means actual working days after you subtract weekends, holidays, vacation, and sick days from the calendar.³

An example. You expect 240 workdays this year and plan to be in Connecticut for 60 of them. Your percentage is 25%. That’s what goes on the form, and your employer withholds Connecticut income tax on 25% of your wages instead of the full amount. The closer your estimate matches reality, the smaller your refund or balance due will be at tax time.

Keep a running log of your actual Connecticut days as the year goes on. If your schedule drifts from the estimate, you can file an updated form. And if you’re ever audited, that day-by-day record is the best evidence you have.

Filling Out the Form

The form asks for your full legal name, home address, Social Security number, and your employer’s name and address. These need to match federal records. Enter your Connecticut work percentage, sign under penalty of false statement, and give the form to your employer’s payroll or human resources department.³

Do not mail the CT-W4NA to the Department of Revenue Services. It stays with your employer, who applies the percentage to your payroll withholding and keeps the form on file. The employer also has an ongoing duty to monitor the estimate. If they know or have reason to know your percentage is no longer accurate, they must adjust withholding even without a new form from you.¹

The current version is posted on the Connecticut DRS website under withholding forms. A 2026 edition has been published, so make sure you’re pulling the latest one.

How It Works With Form CT-W4

The CT-W4NA doesn’t replace Connecticut’s regular withholding form. You need both. Form CT-W4 tells your employer your filing status and withholding code, which sets the base amount of Connecticut tax calculated on your wages. The CT-W4NA then applies your work percentage to that base. If you haven’t completed a CT-W4 yet, do that first.³

In practice, your employer runs the CT-W4 calculation on your total wages, then multiplies that result by your CT-W4NA percentage. The product is the Connecticut tax pulled from each paycheck.¹

What Happens If You Don’t File It

Without a CT-W4NA on file, and without independent employer records showing where your work happens, your employer must withhold Connecticut income tax on all wages paid to you. Every day is treated as a Connecticut day.¹

If you actually work in Connecticut only part of the time, that’s a much bigger bite out of each paycheck than you owe. You’ll get the overpayment back as a refund on your annual nonresident return, but months of your money sits with the state in the meantime. Filing the form upfront is the simple fix.

Updating the Form When Things Change

Your original percentage is an estimate. Schedules shift. If a project extends your Connecticut time significantly, or an assignment gets canceled and your Connecticut days drop, submit a revised CT-W4NA as soon as you can see the change. That lets payroll adjust in real time rather than leaving you with a large surprise at year end.

Update it too if something changes on your CT-W4, such as your filing status. The two forms work together, so a change to one can throw off the other.

Situations Where the Rules Are Different

A few common scenarios don’t fit the standard nonresident apportionment picture, and it’s worth knowing where they land before you fill out a percentage.

Remote work for a Connecticut employer. Connecticut applies a “convenience of the employer” rule on a reciprocal basis. If you live in a state that has its own convenience rule (New York is the main one), Connecticut treats your remote workdays as Connecticut-sourced unless the remote arrangement exists because your employer requires it, not because you prefer it. If your home state has no such rule, Connecticut generally won’t tax wages earned while you were physically working from home.¹ For a reciprocal-rule resident, the percentage on your CT-W4NA may need to reflect more than just the days you physically crossed into Connecticut.

Occasional visits for meetings or training. Under Connecticut’s ancillary activity test, presence in the state is treated as incidental when it’s secondary to your primary duties performed at a base of operations elsewhere. Qualifying activities include occasional trips for management reporting, planning, training, conferences, and board meetings.⁴ Wages earned during ancillary visits aren’t Connecticut-sourced.

Military spouses. Under the federal Military Spouses Residency Relief Act, if you’re in Connecticut solely because your service member spouse is stationed there, you can keep legal residency in another state for income tax purposes. Your Connecticut wages are then taxed by your state of legal residence, and a CT-W4NA isn’t needed for them.

Reconciling at Tax Time

The CT-W4NA governs your withholding during the year, but it doesn’t replace your annual return. When you file Connecticut Form CT-1040NR/PY, you match what was withheld against what you actually owe based on your real Connecticut-sourced income. The Connecticut tax withheld from your W-2 goes on Line 20 of that form.⁵

The return is due April 15 following the tax year, with an automatic extension available to October 15. An extension gives you more time to file, not to pay.⁶ If your CT-W4NA percentage was close to your actual work pattern, the settle-up will be small. If the percentage was well off, this is where the difference shows.

Check whether your home state offers a credit for income taxes paid to Connecticut. Most do, which prevents double taxation on the same income. You claim it on your home state return by reporting the Connecticut tax you paid.

1
Connecticut Department of Revenue Services. IP 2026(1) Connecticut Employer’s Tax Guide, Circular CT
2
Justia Law. Connecticut Code 12-705 – Withholding Tax
3
Connecticut Department of Revenue Services. Form CT-W4NA Employee’s Withholding Certificate – Nonresident Apportionment
4
Legal Information Institute. Connecticut Agencies Regulations 12-711(b)-4 – Business, Trade, Profession or Occupation
5
Connecticut Department of Revenue Services. 2025 Form CT-1040NR/PY Instructions
6
Connecticut Department of Revenue Services. DRS 2026 Tax Filing Due Dates Calendar