Get your tax IDs in Connecticut

An EIN, if you need one, takes minutes online. Connecticut then adds a sales tax permit if you sell taxable goods or a taxable service, withholding if you have employees, and an unemployment account once you are a covered employer. The old business entity tax is not on that list.

What’s different in Connecticut

• Sales tax is a state rate, not a local one. 6.35% on most sales. No Connecticut city or town adds its own sales tax¹. Meals, computer services and some expensive goods use other rates.
• The permit is $100¹, and you need it before the first sale. Building contractors need one even when the service is not taxable.
• The business entity tax has ended. Corporation business tax remains a separate obligation for C corporations, and the pass-through entity tax is optional.
• A calendar-year corporation files on May 15, later than the federal return. The tax is at least $250⁴.
• Unemployment tax in 2026 applies to the first $27,000 of each employee’s wages. The new-employer rate is 1.9%¹². Details are below.

Do this

1. Get an EIN from the IRS if you need one. It is free and, if approved, issued immediately¹⁶ online. Don’t pay a website to apply for you. A sole proprietor with no employees may be able to use a Social Security number. Connecticut’s registration page asks for the business's EIN, or the owner's Social Security number for a sole proprietor. Any other business without an EIN has to get one from the IRS first².
2. Register for sales tax on myconneCT if you will sell in Connecticut. The permit is $100. You get a Sales and Use Tax Permit. Get it before you make any sales. It covers anyone selling, renting, or leasing goods, selling a taxable service, or operating a hotel, motel, lodging house, or bed and breakfast, including manufacturers and wholesalers. Casual or isolated sales, infrequent and nonrecurring, by someone not in the business of selling, do not need the permit¹. Building contractors, including subcontractors, need a permit before they provide any services, even when the service is not taxable or the customer is tax-exempt. You need a permit for each location, and a buyer of a business cannot use the seller's permit².
3. Use the rate for what you sell, not one number for everything. The sales tax page lists them. Most goods and taxable services are 6.35%. Computer and data processing services are 1%. Meals and certain beverages are 7.35%. The 7.75% rate applies to most motor vehicles, to jewelry, and to some clothing, footwear and bags, once the price passes the thresholds printed on that page. The same page also lists rates for vessels, a motor vehicle sold to certain military members, and a short-term passenger-car rental. No Connecticut city or town adds its own sales tax¹.
4. A seller outside Connecticut registers once it passes both thresholds. The test is 200 retail sales into Connecticut and at least $100,000 in gross receipts, counted for the 12 months ending on the September 30 before the period the tax is figured for. Both have to be true. Marketplace facilitators and marketplace sellers may have to get a permit. An out-of-state seller with goods at a marketplace facilitator in Connecticut must register even when it is under the sales thresholds².
5. File Form OS-114 on the schedule DRS assigns. Filing is monthly, quarterly, or annual, assigned by DRS. The return is due the last day of the month after the period ends. File even when you had no sales and no tax is due. Doing business without the permit costs $250 the first day and $100¹ each following day. The sales tax page does not state the penalty for a late return when you already have the permit.* Check it in myconneCT before you file late.
6. Register for corporation business tax if you are a C corporation. File Form CT-1120. The tax is the greater of the net income base tax and the capital base tax. Net income is taxed at 7.5%. The capital base was taxed at 0.21% for the 2025 income year. The statute lowers that to 1.6 mills per dollar (0.16 percent) for an income year that starts in 2026, 1.1 mills (0.11 percent) for one that starts in 2027, and zero from 2028⁵. The tax cannot be less than $250. Some companies also pay a 10 percent surtax on the tax, if federal total income is 100 million dollars or more, or if the company files in a combined unitary group. That surtax runs through the income year that begins on or after January 1, 2028. A calendar-year return is due May 15. A return for a year that ends June 30 is due October 15. Estimated payments start when the year’s tax is expected to exceed $1,000. A late payment is 10 percent of the tax due or 50 dollars, whichever is greater⁴. The business entity tax no longer exists, for any tax period beginning after December 31, 2018³.
7. Decide whether a pass-through entity will elect the entity tax. It applies to a partnership or an S corporation, including an LLC taxed as one of those. The tax is optional, made each year, and irrevocable for that year. You elect by this step: Check the box on a timely Form CT-1065/CT-1120SI. The 2025 return computes the tax at 6.99%. It is due March 15 for a calendar-year filer. The return and the payments are filed and paid electronically⁶. Schedule D of the 2025 return gives members a credit of 87.5%⁷ of the entity tax allocated to them. Read the form before you elect. Whether the election helps depends on your numbers. Ask a CPA. This page does not pick it for you. A single-member LLC that is not taxed as a partnership or an S corporation is outside the definition on that page. Check which Connecticut return that owner’s income uses.
8. Register for withholding when you have employees. DRS says you generally register when you employ one or more workers in your business². Start at the registration page. The withholding page lists due dates for weekly, monthly and quarterly¹⁰ payers. It does not say which schedule a new employer starts on.* Check yours in myconneCT. The hiring guide covers the federal side. Report each new hire within 20¹¹ days of hiring, through the state’s new hire reporting page.
9. Open unemployment tax when you are a covered employer. The 2026 wage base is $27,000. The rate table prints a new employer rate of 1.9%, a minimum of 1.1% and a maximum of 9.9%. The 2026 notice says the new employer rate falls from 2.2 percent to 1.9 percent. The same notice says the fund solvency tax is 1%, the minimum charged rate is 0.1%, and the 2026 maximum charged rate is 8.9%. Contribution rates are 1.1 percent to 9.9 percent. The notice does not say whether the 1.9% new-employer rate already includes the solvency tax.* Do not add 1%¹³ on top of 1.9%¹² until the rate notice says to. The Department of Labor says every employer of one or more people, full or part-time, must register online in ReEmployCT. An employer generally becomes liable for the tax once it pays $1,500 or more in wages in a calendar quarter, or has at least one person working for some part of a day in each of 20 different weeks¹⁴, in the current or preceding calendar year. Reports are due quarterly, on April 30, July 31, October 31 and January 31, with a late fee of up to $25¹⁵ a quarter.

Income tax for owners

Owners who report the business on their own return use the Connecticut income tax brackets. The 2025 tax calculation schedule is for the 2025 taxable year. For a single filer or a married person filing separately, the top band is 6.99% above the highest threshold on that schedule. For a joint return, the top band is 6.99 percent on taxable income over 1,000,000 dollars⁸. Head of household uses its own bands on that schedule. DRS’s resident income tax page gives April 15, 2026⁹ as the due date for the 2025 return. This page does not estimate your tax.

Buying an existing business can pull in the seller’s unpaid taxes. DRS says to notify it by letter at least 90² days before the closing and ask for a tax clearance. The clearance is issued to the buyer.

What you get back

An EIN from the IRS if you applied, a sales and use tax permit if you registered, a corporation or pass-through account if that tax applies, a withholding account if you have employees, and an unemployment account once you are covered. Write down the sales tax filing frequency DRS assigns. It is not something you choose.