Connecticut Withholding Tax for Employers: CT-W4 and CT-941

Connecticut withholding tax requirements for employers cover five moving parts: registering with the Department of Revenue Services (DRS), collecting a Form CT-W4 from every employee, calculating the right amount using the state’s progressive rates of 2% to 6.99%, depositing the tax electronically on the schedule DRS assigns you, and reconciling everything quarterly on Form CT-941 and annually on Form CT-W3 with W-2s.¹ Miss any of it and you are looking at a 10% penalty, 1% monthly interest, and, if withheld money never reaches the state, personal liability for the officers or owners who controlled the funds.

Register With DRS Before the First Paycheck

If your business maintains an office or conducts business in Connecticut and qualifies as an employer for federal withholding purposes, you must register for Connecticut withholding. That is true even when payroll is run entirely out of state.² Registration happens through myconneCT, the DRS online portal. Businesses already registered for other Connecticut taxes can add withholding as an additional liability from the same account.

Registration produces a Connecticut Tax Registration Number, which is not the same as your federal EIN or your Department of Labor number. All three exist for different purposes, and the DRS number has to appear on every withholding form and letter you send DRS.¹

Get a CT-W4 From Every Employee

Every employee performing services in Connecticut must complete Form CT-W4, the Connecticut Employee’s Withholding Certificate. It tells you their filing status code and any additional or reduced withholding they have requested. Your withholding duty starts with the first payment of wages, so the form needs to be in hand before that first check runs.³

No completed CT-W4 on file means you do not guess. Connecticut requires withholding at the top marginal rate of 6.99% with no exemption applied.³ That default is painful for employees, so chase down missing forms early. Watch too for additional withholding requested on Line 2 or reduced withholding claimed on Line 3.

Calculating the Withholding

Connecticut does not offer a flat-rate option for regular wages. You use either the wage-bracket tables in Circular CT (the state’s Employer’s Tax Guide) or the exact calculation method it publishes.³ The exact-calculation path runs like this:

Annualize the pay-period gross wages by multiplying by the number of pay periods in the year.
Subtract the personal exemption for the employee’s filing status and wage level from the CT-W4.
Apply the seven progressive brackets, running from 2% at the bottom to 6.99% above the top threshold. Bracket widths differ by filing status code; Code C (married filing jointly) has wider brackets than Code F (single).
Adjust for the personal exemption phase-out that hits higher earners.
Divide the annual tax by the number of pay periods to get the per-check amount.

The result cannot be negative. If the math falls below zero, withholding for that pay period is zero. Use the current year’s Circular CT because tables and exemption amounts change with new legislation.

Supplemental Wages Follow a Different Path

Bonuses, commissions, and overtime do not get a flat percentage in Connecticut, which is where employers most often get it wrong. When supplemental pay goes out with the regular paycheck, treat the total as one payment and withhold on the combined amount. When it goes out separately, compute the tax on regular plus supplemental combined, subtract what you already withheld from the regular wages, and withhold the difference from the supplemental payment. If nothing was withheld from regular wages, add them together and compute tax on the whole.³

Deposit Schedule and Electronic Payment

How often you remit depends on how much you withheld during a 12-month look-back period. Three tiers apply:³

Weekly remitter, more than $10,000 in the look-back: pay by the Wednesday following the weekly pay period.
Monthly remitter, more than $2,000 but not more than $10,000: pay by the 15th of the month following the month wages were paid.
Quarterly remitter, $2,000 or less: pay by the last day of the month following the end of the calendar quarter.

Every payment goes through myconneCT by electronic funds transfer. Paper checks are not accepted unless DRS has granted a waiver on Form DRS-EWVR.¹ Weekly and monthly remitters typically pair the payment with Form CT-WH, the Connecticut Withholding Tax Payment Form.

Quarterly and Annual Reconciliation

Depositing on time is only half the job. You also have to reconcile what you withheld against what you deposited, both quarterly and annually.

Form CT-941 (Quarterly)

Every registered employer files CT-941 each quarter, even in quarters with no wages and no withholding. A seasonal employer that temporarily stops paying wages still files rather than closing the account.⁴ Deadlines: April 30 (Q1), July 31 (Q2), October 31 (Q3), and January 31 (Q4). File through myconneCT. If deposits already covered the full quarterly tax, you may have an additional ten days beyond the standard deadline to file the return. Any gap between withholding and deposits produces either a final payment or a credit carried forward. To correct a filed CT-941, file CT-941X promptly rather than waiting for annual reconciliation.

Form CT-W3 and W-2s (Annual)

By January 31 of the following year, file Form CT-W3, the Annual Reconciliation of Withholding, together with the state copies of every federal W-2 issued.⁵ The W-2 totals must match the CT-W3 exactly. Electronic filing applies regardless of headcount.

Non-Residents and Remote Workers

Connecticut withholding applies to non-residents only for wages tied to services actually performed in the state. If a non-resident employee works entirely outside Connecticut, no Connecticut withholding is due, even when the employer’s headquarters or payroll is in Connecticut.¹ For employees who split time between states, apportion the withholding to the Connecticut share of total wages. Form CT-W4NA helps make that calculation.

Connecticut has no reciprocal agreements with other states, so a non-resident from New York or Massachusetts working in Connecticut still has Connecticut tax withheld.⁶

The state also applies a convenience-of-the-employer rule on a reciprocal basis. When a non-resident works remotely for a Connecticut employer, the wages are treated as Connecticut-sourced only if the employee’s home state applies its own convenience rule. In practice this mainly reaches non-residents living in New York.⁷ If the employee’s home state has no convenience rule, Connecticut does not impose one either.

Penalties, Interest, and Personal Liability

Connecticut’s penalty structure stacks, and the exposure is worth knowing before something slips.

A late or short payment triggers a 10% penalty on the amount due. A late return with no tax owed still draws a $50 penalty. Interest runs at 1% per month, or any fraction of a month, from the original due date until paid.⁸

Filing or paying on paper without a waiver draws a separate, graduated penalty: 10% capped at $2,500 for a first offense, 10% capped at $10,000 for a second, and 10% with no cap for the third and beyond.⁸

The exposure that hurts most is personal. Withheld income tax is treated as a trust fund tax. Under Connecticut General Statutes § 12-736, any individual with the duty and authority to collect, account for, or pay over that tax can be personally liable for the full unpaid amount. That reaches corporate officers, directors, shareholders with authority over funds, partners, LLC members, and payroll service providers.⁹ Delaying a deposit to solve a cash-flow squeeze is how business tax problems turn into personal ones.

Records, Closing, and Sales of the Business

Keep payroll and withholding records at the place of employment for at least three years per employee: the CT-W4, the calculation backup for each pay period, myconneCT deposit confirmations, and filed copies of every CT-941 and CT-W3. Clean records are the strongest defense against an assessment.

If the business closes or permanently stops paying wages, file a final CT-941 for the current quarter through myconneCT, issue W-2s to all employees, file CT-W3 with the state copies, and close the withholding account through the Taxpayer Updates section of myconneCT.¹⁰ Also cancel the Department of Labor registration if the business had employees.

A buyer of a Connecticut business inherits withholding tax exposure. If the seller owes withholding tax, the buyer must hold back enough of the purchase price to cover the taxes, interest, and penalties until the seller produces a DRS receipt showing the account is clear. A buyer who fails to hold back becomes personally liable for the unpaid taxes up to the purchase price.¹¹

1
Connecticut State Department of Revenue Services. 2026 – Withholding Tax Information
2
Connecticut State Department of Revenue Services. New Employer Information
3
Connecticut Department of Revenue Services. IP 2026(1) – Connecticut Employer’s Tax Guide
4
Legal Information Institute. Conn. Agencies Regs. 12-707-1 – Schedule for Filing Withholding Tax Returns and Payment of Taxes
5
Connecticut Department of Revenue Services. DRS 2026 Tax Filing Due Dates Calendar
6
Connecticut General Assembly. State Income Taxes on Income Sourced to Other Jurisdictions
7
Connecticut General Assembly. Convenience of the Employer Rule
8
Connecticut State Department of Revenue Services. Other Helpful Information
9
Connecticut Department of Revenue Services. Can I Be Held Personally Liable For Payment of Business Taxes
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Connecticut State Department of Revenue Services. Other Helpful Information
11
Justia Law. Connecticut Code Title 12 – Section 12-707