Stamford Business Filing Deadlines & Ongoing Requirements

Annual federal income tax return (extensions available via Form 7004 / 4868).

Free, one-time federal tax ID needed for tax filings, payroll and bank accounts.

Fee: $80. Required to keep the entity in good standing.

Businesses holding property that has gone unclaimed — uncashed payroll or vendor checks, customer credits and refunds, unused gift cards, deposits — must report and turn it over to the state each year, after sending the owner a due diligence notice before the deadline. The annual report and payment are due March 31 for general property. A negative report is required even when the business holds nothing. The directory page says March 30; other sources say March 31. Which state's law applies depends on the owner's last known address, or the business's state of incorporation when there is none, so a business can owe reports to several states.

A person or service with a physical Connecticut address to receive legal notices and service of process; listed with Connecticut Secretary of the State.

Corporation Business Tax; optional Pass-Through Entity Tax.

If personal information of residents of the state is acquired without authorization, notify affected residents within 60 days of discovering the breach (Conn. Gen. Stat. 36a-701b). This is an event-driven duty, so it has no calendar date. Sources in the PR describe the state's rule in different words; check the statute for the exact trigger and content of the notice.

Connecticut has no general local business license; trade names are registered with the town clerk.

The commercial space must be approved for its intended use before operating.

Withheld income tax, Social Security and Medicare, plus employer share, via EFTPS.

Quarterly reconciliation of wages and payroll taxes.

Annual FUTA return and payment.

Wage statements to employees and transmittal to the SSA.

Employment eligibility verification, retained for 3 years after hire or 1 year after termination.

Employers must post the FLSA minimum wage, FMLA (50+ employees), EEO, OSHA, USERRA and related notices in a conspicuous place.

Employer account for state unemployment insurance contributions.

Withhold state income tax from wages and remit on the assigned deposit schedule; file annual reconciliation and W-2s.

Quarterly wage report and contribution payment. Connecticut taxes the first $27,000 of each employee's wages (2026); new employers pay 1.9%, and experience-rated rates range from 0.1% to 10%.

Federal law requires reporting each new hire within 20 days of hire (some states require sooner).

Required at: 1 employee.

Employers withhold 0.5% of wages and remit quarterly.

State minimum wage, unemployment insurance, workers' compensation and anti-discrimination notices must be posted where employees can see them.

Employers with three or more employees must give two hours of training to all employees within six months of hire, and to supervisors regardless of employer size; supplemental training is required periodically (sources say every 10 years or every three).

Private employers with five or more employees (at least five earning $5,000 or more in the prior year) and no qualified plan must offer MyCTSavings or certify an exemption on the portal. Deadlines moved from March 30, 2023 to August 31, 2023 and then annual; the current date was not confirmed. A 2023 law-firm alert found no penalty for failing to certify.

Employers with more than 10 employees keep Forms 300 and 301 for work-related injuries and illnesses, and post the Form 300A summary for the previous year at each establishment from February 1 through April 30. Records are kept five years. Report a work-related fatality within 8 hours and an inpatient hospitalization, amputation or loss of an eye within 24 hours.

Applicable large employers (50 or more full-time employees, counting part-time hours as full-time equivalents) give each full-time employee a Form 1095-C. The January 31 deadline is extended automatically by 30 days, to March 2 in most years (March 1 for the 2026 forms).

The transmittal Form 1094-C and each Form 1095-C are due to the IRS at the end of February on paper or March 31 electronically; employers filing 10 or more information returns in total must file electronically. Penalties apply per late or incorrect form.

Connecticut requires employers with 25+ employees to provide paid sick leave, post notice and keep records.

Private employers with 100 or more employees file annually through the EEOC's online system; federal contractors with 50 or more employees and certain contracts have also filed. The EEOC sets each year's window (the 2024 report was due June 24, 2025, with no extensions), so check its data collections page.

Establishments with 250 or more employees submit their Form 300A summary through OSHA's Injury Tracking Application by March 2. Establishments with 20 to 249 employees in designated higher-hazard industries must also submit the summary, and those with 100 or more in the most hazardous industries submit Forms 300 and 301 data.

Quarterly estimated payments by owners on business income (Form 1040-ES), including self-employment tax.

Connecticut applies the ABC test to unemployment insurance and, per one policy group's table, wage and hour rules; a worker who fails any prong is an employee.

Required for each non-employee paid $2,000 or more in the year (payments made after 2025).

Required before making taxable sales; register with the state tax agency.

Collect sales tax from customers and remit on the filing frequency assigned by the state.

Home-based businesses need a home occupation permit and must comply with zoning limits (signage, customers, employees).

Connecticut registers sole proprietors' and partnerships' assumed names at the town level, in each town where business is conducted.