Quarterly Estimated Taxes for Connecticut Small Business Owners

Running your own business means nobody withholds taxes from your income for you. That is where quarterly estimated taxes come in.

If you are self-employed, run an LLC, or own a small business in Connecticut, you are likely required to pay quarterly estimated taxes in Connecticut, both to the IRS and to the state. Missing a payment does not just delay what you owe. It adds penalties and interest on top of it.

This guide breaks down who has to pay, how much, when it is due, and what happens if you get it wrong.

Who Has to Pay Quarterly Estimated Taxes in Connecticut?

You generally need to make quarterly payments if you expect to owe:

• $1,000 or more in Connecticut income tax for the year, after credits and withholding
• $1,000 or more in federal tax for the year, after withholding

This applies to:

• Sole proprietors and single-member LLC owners
• Partners in a partnership
• S-corp shareholders who take distributions beyond payroll
• Anyone with significant self-employment or 1099 income

If your only income is a W-2 job with taxes withheld, you likely do not need to file estimated payments. Once you add business income on top of that, the math changes.

2026 Connecticut and Federal Due Dates

Connecticut and the IRS both run on the same quarterly schedule:

• April 15, 2026 (Q1)
• June 15, 2026 (Q2)
• September 15, 2026 (Q3)
• January 15, 2027 (Q4)

Each payment covers roughly three months of income, not a calendar quarter exactly. Q2 and Q4 are shorter windows than Q1 and Q3. Mark all four dates on your calendar at the start of the year so none of them catch you off guard.

How Much Should You Pay Each Quarter?

Most small business owners use one of two methods to calculate their payment:

• Prior-year safe harbor: Pay at least 90% of what you owed last year, split into four payments. If your income is similar year to year, this is the simplest and safest option.
• Current-year estimate: Project your actual income for the year and pay 25% of the projected total each quarter. This works better if your income is growing or highly variable.

Connecticut follows the same safe harbor logic as the IRS. Paying based on last year’s liability protects you from underpayment penalties even if this year turns out to owe more. You settle the difference when you file your annual return.

What Happens If You Miss a Payment or Underpay?

Missing or underpaying a quarterly estimate does not erase the obligation. It adds to it.

Underpayment triggers:

• Interest charged on the shortfall from the due date forward
• A separate underpayment penalty calculated by the IRS and Connecticut DRS
• A larger, unexpected balance due when you file your annual return

The penalty applies even if you pay everything owed by April 15 the following year. The IRS and Connecticut DRS calculate the penalty based on when each quarterly payment was due, not just the annual total.

How to Calculate and Submit Your Payment

For federal estimated taxes, you calculate your payment using IRS Form 1040-ES and submit electronically through IRS Direct Pay or by mail.

For Connecticut, you use Form CT-1040ES and submit through the myCTDRS portal or by mail. Connecticut requires quarterly payments once you expect to owe $1,000 or more for the year, same threshold as the federal rule.

Getting the calculation right matters more than getting it done quickly. Overpaying ties up cash you need in your business. Underpaying triggers the penalties above. A tax professional who reviews your actual numbers each quarter (not just a flat percentage guess) keeps you accurate without overpaying.

Why Small Business Owners Choose JUMA for Quarterly Tax Planning

Quarterly taxes are not a once-a-year task. They need to be checked against real numbers four times a year, not estimated once in January and forgotten.

When you work with JUMA, you get:

• Quarterly income review so your payment reflects what you actually earned, not a flat guess
• Calculation and filing support for both federal Form 1040-ES and Connecticut CT-1040ES
• Reminders before each due date so you never miss a quarter
• Year-round access, not just a tax-season relationship
• Bilingual service in English, Spanish, and Kreyol
• ITIN and business-structure guidance if you are still formalizing your business

Our clients come to us once for a quarterly payment question and stay because they no longer have to think about the deadline themselves.

Proudly Serving Waterbury and Surrounding Communities

JUMA works with small business owners throughout Waterbury and the surrounding towns, including Middlebury, Naugatuck, Wolcott, Cheshire, Prospect, and Watertown.

Wherever your business is registered, if you are self-employed or running a small business in Connecticut, the same quarterly estimated tax rules apply to you.

JUMA handles this for small business owners throughout Waterbury and the surrounding area, alongside bookkeeping, tax preparation, and business startup services.

Call (203) 951-0955 or schedule your appointment online below.