Connecticut sole proprietorship compliance calendar 2026: the filings and due dates
The federal and Connecticut filings a sole proprietorship based in Connecticut owes in 2026, assuming a calendar year, no employees, and no other states, and no revenue figure, which hides the lines that depend on one. Change any of that below and the calendar changes with it.
January 2026
April 2026
June 2026
September 2026
No fixed date
- Beneficial ownership report: not required for US formed companies: Nothing to file. Companies formed in a US state are exempt. A company formed under foreign law and registered to do business in a US state still reports.
The calendar grows with the company
- If you pay independent contractors: 1099-NEC forms to contractors and the IRS
- If you run payroll yourself instead of through a provider: Federal payroll tax deposit, Connecticut annual withholding reconciliation, Connecticut harassment prevention training (3 or more employees), Connecticut Paid Leave contributions, Connecticut unemployment insurance wage report, Annual federal unemployment tax return, Federal unemployment tax deposit, Quarterly federal payroll tax return, W-2 forms to employees and the SSA
- If you collect sales tax in Connecticut: Connecticut sales tax return
- If you offer a retirement plan: Annual retirement plan return, Summary annual report to plan participants
- If you reach 50 employees: Connecticut annual withholding reconciliation, Connecticut harassment prevention training (3 or more employees), Connecticut Paid Leave contributions, Connecticut unemployment insurance wage report, Post the OSHA injury and illness summary, Annual federal unemployment tax return, Quarterly federal payroll tax return, W-2 forms to employees and the SSA, Health coverage statements to employees, Submit injury and illness data to OSHA, Health coverage returns to the IRS
- If you hold a bank account outside the US: Report of foreign bank and financial accounts
- If you pay people or companies outside the US: Withholding returns for payments to foreign persons
Each filing, in plain English
Owner's estimated tax payment
When: on April 15, June 15, September 15, January 15. Where: IRS (Form 1040-ES). If missed: An underpayment penalty computed on Form 2210, charged as interest on each short installment.
A sole proprietor or single member LLC owner pays income tax and self employment tax on the business profit through their own return, and the IRS wants it paid during the year. An owner who expects to owe $1,000 or more pays in four installments: April 15, June 15, September 15 and January 15 of the following year. Withholding from a job or a spouse's salary counts toward the total.
Business income on the owner's personal return
When: by April 15 each year. Where: IRS (Form 1040, Schedule C and Schedule SE). If missed: 5% of the unpaid tax for each month late, up to 25%, plus interest.
A sole proprietorship or single member LLC has no return of its own. Its income and expenses go on Schedule C with the owner's personal return, due April 15, and the owner pays self employment tax on the net profit through Schedule SE. An LLC owned by a person outside the United States is different: see the nonresident owner's return.
Connecticut personal income tax return with business income
When: by April 15 each year. Where: Connecticut Department of Revenue Services.
A sole proprietorship or single member LLC reports its income on the owner's Connecticut personal return, due April 15 each year in step with the federal Form 1040.
Make it yours
Put it in your calendar
The calendar is free to read and to print. A subscription keeps it alive.
- Every date in Google Calendar, Outlook or Apple Calendar, updated when a rule changes
- Email reminders 30 days, 7 days and 1 day before each date, and on the day
- Your bookkeeper, your office manager, your CPA: invite anyone, unlimited
- Mark each filing done and keep a filing record you can send a lender or a buyer
- Every change in federal or state rules that touches your company, explained
- Jay's plain English notes on every obligation
Advisors: $49 a month for up to ten companies, $4 each after. Details