Connecticut Form CT-W4NA: Nonresident Work Percentage Withholding

Connecticut Form CT-W4NA is the certificate a nonresident employee gives their employer to apportion Connecticut income tax withholding to only the share of wages earned from work actually performed inside the state. Without it, your employer is required to withhold Connecticut tax as if every workday happened in Connecticut, which can mean hundreds of extra dollars pulled from each paycheck.¹

Who Should File It

Any nonresident employee who splits working time between Connecticut and another state should file this form. Connecticut law requires every employer with an office or business presence in the state to withhold income tax on wages paid for services performed there, for residents and nonresidents alike.² The CT-W4NA gives payroll the number it needs to withhold on only your Connecticut portion.

One threshold matters before the form does. If you expect to work in Connecticut 15 days or fewer during the calendar year, that pay is not Connecticut-sourced and no withholding is required. Cross the line, though, and the rule flips completely: your employer must withhold on all compensation for services performed in Connecticut, including the first 15 days.¹ If your schedule is anywhere near borderline, start tracking days from January.

Calculating Your Connecticut Work Percentage

The whole form turns on a single number: the percentage of your working time you expect to spend in Connecticut this calendar year. Divide the days you expect to work in Connecticut by your total expected workdays, which is the calendar year minus weekends, holidays, vacation, and sick days.³

An example. If you expect 240 total workdays and plan to be in Connecticut for 60 of them, your percentage is 25%. That goes on the form, and your employer withholds Connecticut tax on 25% of each paycheck instead of 100%.

Keep a contemporaneous log of your actual Connecticut days as the year goes on. Two reasons: your estimate rarely survives the year unchanged, and if the Department of Revenue Services ever asks how you got your number, that day-by-day record is your best evidence.

How It Works with Form CT-W4

The CT-W4NA does not stand alone. You also need a Form CT-W4 (the standard Employee’s Withholding Certificate) on file, because that form sets your filing status and withholding code. The payroll math goes in order: the employer calculates the total Connecticut tax on your full wages using the CT-W4, then multiplies that amount by the percentage from your CT-W4NA. The product is what actually comes out of your check.³¹ If you haven’t filed a CT-W4 yet, do that first.

Filling Out and Submitting the Form

The form itself is short. You enter your legal name, home address, Social Security number, and your employer’s name and address, then the Connecticut work percentage you calculated. Make sure the identifying information matches what the federal government has on file. Sign under penalty of false statement and give the form to your employer’s payroll or HR team.³

Do not mail it to the Department of Revenue Services. The form stays with your employer, who keeps it on file and uses the percentage to run your payroll. The employer also has an independent duty to adjust withholding if they know, or have reason to know, that your estimate no longer matches reality, even without a new form from you.¹

Download the current version from the Connecticut Department of Revenue Services website under withholding forms. A 2026 edition has been published, so use the newest one available.

What Happens If You Don’t File It

If a nonresident employee doesn’t provide a CT-W4NA and the employer doesn’t separately keep records showing how the employee’s time is split, the employer must withhold Connecticut income tax on every dollar of wages, as if the entire job were performed in Connecticut.¹

You’d eventually get the overpayment back as a refund after filing your nonresident return, but you’d be out of pocket for months in the meantime. For anyone who only works part of their time in Connecticut, filing the form upfront is the simple way to keep your paychecks accurate.

Updating the Form Mid-Year

Your first filing is an estimate. If a project stretches and your Connecticut days climb well above what you projected, or an assignment is canceled and they drop, submit a revised CT-W4NA to your employer so payroll can adjust in real time. The same goes if something changes on your CT-W4 (filing status, for instance), since the two forms work together and a shift in one can throw off the other.

Because you sign the form under penalty of false statement, honest projections and real records matter.³ The realistic risk for most employees isn’t prosecution; it’s an audit that turns up a wide gap between the percentage reported and the days actually worked, with no supporting log to explain it.

Situations That Change the Answer

A few situations shift whether you need the form at all, or change the percentage you’d put on it.

Occasional Visits for Meetings or Training

Under what Connecticut regulations call the “ancillary activity test,” your presence in Connecticut is treated as incidental when it’s secondary to primary duties performed at a base of operations outside the state. Qualifying activities include occasional trips for management reporting, planning sessions, training, conferences, and board meetings.⁴ Wages earned on those visits aren’t Connecticut-sourced, and no CT-W4NA is needed to cover them.

Remote Work for a Connecticut Employer

Connecticut applies a “convenience of the employer” rule, but only on a reciprocal basis. If you live in a state that has its own convenience rule and you work remotely for a Connecticut employer, Connecticut will treat your remote days as Connecticut-sourced unless you can show the remote arrangement exists because your employer needs you to work from that location rather than because you prefer it.¹ This mostly affects New York residents. If your home state doesn’t have a convenience rule, Connecticut generally won’t tax the wages you earned while actually working from home, so your CT-W4NA percentage reflects only the days you physically worked in Connecticut.

Military Spouses

Under the federal Military Spouses Residency Relief Act, a spouse who is in Connecticut solely because their service member is stationed there can keep legal residency in another state for income tax purposes. Wages earned in Connecticut are then taxed by the state of legal residence, not Connecticut, and no CT-W4NA or Connecticut nonresident return is needed for them.

Year-End Reconciliation

The CT-W4NA controls your paycheck withholding; it doesn’t finalize your tax. At year end, you file Form CT-1040NR/PY and reconcile what was withheld against what you actually owe based on the Connecticut days you really worked.⁵ The return is due April 15, with an automatic extension to October 15 available for filing (not for paying).⁶

Even with a good CT-W4NA on file, you may still need to make quarterly estimated payments if you expect to owe $1,000 or more to Connecticut after withholding and any pass-through entity tax credit. The required annual payment is the lesser of 90% of your current-year Connecticut tax or 100% of your prior-year tax (if that return covered a full 12 months).⁷ Bonuses and commissions are the usual reasons withholding falls short mid-year.

Finally, check your home state’s rules for a credit for taxes paid to another state. Most states offer one, and claiming it on your home state return is how you avoid being taxed twice on the same Connecticut-sourced wages.

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
7
Connecticut State Department of Revenue Services. Tax Information