Sales tax filing Connecticut: how to file Form OS-114

Form OS-114 is the return, not a CT-1

The Connecticut sales and use tax return is Form OS-114, Sales and Use Tax Return. Its instructions are Form O-88, revised 07/26, and the same return reports both sales tax and business use tax. A CT-1 reference in an old folder or a search result is a mismatch. Check the current revision on the DRS forms page before preparing anything.

Check the Connecticut Tax Registration Number, the Federal Employer Identification Number and the period end date against the account before entering any figure.

The frequency is assigned by DRS from prior-year liability

Every registered business reports on a monthly, quarterly or annual frequency that DRS assigns. Form O-88 says taxable and nontaxable sales must be reported in accordance with that frequency, so the period is set by DRS and not by the firm. The Registration Confirmation letter and the myconneCT account both show the Filing Frequency.

DRS's 2019 Getting Started in Business presentation describes how the frequency is set. New applicants start monthly. After that, DRS looks at the sales tax liability for the prior 12-month period, July 1 through June 30. A liability under $1,000 may be switched to annual, from $1,000 to under $4,000 may be switched to quarterly, and over $4,000 may be switched to monthly. The current instructions do not restate those tiers, so confirm them with DRS for each client. DRS monitors filings for 12 months before it changes a frequency, and it notifies the business in writing.

Decision rule: if the account shows a frequency different from the one the client remembers, the account wins. Ask the client for a screenshot of the account page and file under the frequency shown. If a new registration shows no frequency at all, call DRS before the first period closes.

Due dates for 2026 periods

Form O-88 says Form OS-114 is due on or before the last day of the month following the end of the filing period. DRS's 2019 presentation adds that if the due date falls on a Saturday, Sunday or legal holiday, the return is timely if filed and paid by the next business day. Applied to 2026 periods: October 2026 sales for a monthly filer are due November 30, 2026, a Monday. July through September 2026 for a quarterly filer was due October 31, 2026, a Saturday, so the last timely day was Monday, November 2, 2026. The October through December 2026 quarter and the calendar 2026 annual period are due January 31, 2027, a Sunday, which rolls to Monday, February 1, 2027.

Plan to file the fourth-quarter and annual 2026 returns by Friday, January 29, 2027. The roll-forward comes from the 2019 slide and the Rev. 07/26 instructions do not restate it, so filing on Friday removes the question.

Decision rule: if a return is already past due, file it now with the payment. Interest runs from the due date until payment, so each month of delay adds to the bill.

Electronic filing, payment and advance payments

Form O-88 says Form OS-114 is filed and paid electronically using myconneCT, and that annual filers have had to file and pay electronically since periods beginning on or after January 1, 2022. For 2026 periods, every frequency files through myconneCT. Paper is limited to a client granted a one-year waiver on Form DRS-EWVR, Electronic Filing and Payment Waiver Request, and that client pays by check payable to Commissioner of Revenue Services.

A direct payment made at the time of filing is free. A card payment carries a convenience fee generally 2.35% of the payment amount, with a minimum charge of $3.95. Through the Make Payment Only option in myconneCT, a client can pay tax as it is collected. Those advance payments post as a credit on Line 11 when the Form OS-114 is filed.

Failure mode: a client who mails a check without a waiver has not paid electronically. Form O-88 sets a penalty of 10% of the required payment for a first offense, capped at $2,500. The second offense carries 10%, capped at $10,000. Later offenses carry 10%. Set up the myconneCT payment method before the first due date.

Reporting by sales type: the lines

The return is built by sales type, not as one total. Line 1 takes total gross receipts from the sale of tangible personal property. Line 2 takes gross receipts from leasing and renting tangible personal property, and Line 3 takes gross receipts from the rendering of services. Lines 4a, 4b, 5 and 6 pick up purchases subject to use tax.

Line 7 totals Lines 1 through 6. Line 8 takes the nontaxable sales, which must be itemized on the Sales Tax Deductions page. Lines 15 through 17 cover sales for resale and sales through a registered marketplace facilitator. DRS may require certificates from purchasers to support exempt sales, so keep the resale certificates with the workpapers. Line 9 subtracts Line 8 from Line 7. Line 10a multiplies Line 9 by the rate for each column, and Line 11 takes credit for any advance payment for the period.

Line 12 subtracts Line 11 from Line 10. Line 13 adds interest if the return is late or amended, and Line 14 adds Lines 12 and 13 for the total. Round to whole dollars: 1 through 49 cents round down, and 50 through 99 cents round up.

Rates by column, not by line

The rate depends on the column. Column 1 is the general rate of 6.35%, and it also carries the reduced rates: 1% for computer and data processing services, 2.99% for vessels and related items, and 4.5% for a motor vehicle sold to a nonresident member of the armed forces on active duty in Connecticut.

Column 2 is 7.35% for meals and beverages sold for immediate consumption that were previously taxed at the general rate. Column 3 is the 7.75% luxury rate, which applies to most motor vehicles priced above $50,000 and to each piece of jewelry above $5,000. It also applies to each piece of clothing or pair of footwear above $1,000 and to a handbag, luggage, umbrella, wallet or watch above $1,000. Column 4 is 9.35% for rental of a passenger motor vehicle for 30 consecutive days or less.

Worked example: a monthly filer has $30,000 of general taxable sales and $5,000 of meals sold for immediate consumption in October 2026. Column 1 gives $30,000 times 6.35%, or $1,905. Column 2 gives $5,000 times 7.35%, or $367.50, which rounds to $368. The total on Line 14 is $2,273. Failure mode: if the meals go in Column 1, the return computes $317.50 on them and understates the tax by $50.

Penalties and interest

Form O-88 sets the late payment penalty at 15% of the tax due or $50, whichever is greater. Interest is computed at 1% per month or fraction of a month from the due date until payment. Using the October example, if the $2,273 is paid 45 days after November 30, the penalty is $340.95 and the interest is two months at 1%, or $45.46. The payment due is $2,659.41.

Use tax on the same return

A business that buys goods or taxable services for use in Connecticut without paying Connecticut sales tax owes the use tax. Form O-88 says the use tax rates are identical to the Connecticut sales tax rates, and the use tax is reported on the same OS-114.

Decision rule: when a client buys equipment or software from an out-of-state vendor that charged no Connecticut tax, record the tangible purchase on Line 4a or the service on Line 6, and compute the tax at the rate in the column that fits the item.

The checks that prevent a notice

Compare the sales figures on Lines 1, 2 and 3 with the ledger or point-of-sale report for the same period. Confirm that every resale or exempt sale on Line 8 has a certificate on file.

Ask them to log in to myconneCT and send a screenshot of the sales tax account page showing the filing frequency and the next due date. For each period, ask them to separate taxable sales at the general rate, meals sold for immediate consumption, and any item over the luxury thresholds, and to list each purchase where no Connecticut tax was charged.