Morning: Small Business Tax Tips (New Haven): September Tax Deadlines Every Small Business Owner Should Mark Now

September 2, 2026 • News

NEW HAVEN, CT : Jose’s Tax Service : September 2, 2026

September is a critical tax-planning month for small business owners, self-employed professionals, contractors, and employers in New Haven. The September 15, 2026 deadline applies to several important federal and Connecticut tax obligations.

Use this month to complete three priorities:

Pay the third installment of 2026 estimated tax.
Confirm your third-quarter payroll tax deposit schedule.
Organize business records before year-end reporting begins.

Late payments, incomplete payroll records, and unsupported deductions may lead to penalties, interest, filing delays, or inaccurate tax returns.

Mark September 15 for Estimated Tax Payments!

The third federal estimated tax payment for 2026 is due Tuesday, September 15, 2026.

Individuals generally use Form 1040-ES, Estimated Tax for Individuals, to calculate and pay estimated federal income tax. This requirement commonly affects business owners who receive income through:

Sole proprietorships reported on Schedule C (Form 1040).
Freelance or contract work.
Partnerships.
S corporations.
Rental properties.
Investment income.
Other income not subject to sufficient withholding.

The September installment generally covers income earned from June 1 through August 31. However, estimated tax is calculated using your expected annual income, deductions, credits, withholding, and prior payments.

The standard 2026 federal schedule is:

April 15, 2026: First installment.
June 15, 2026: Second installment.
September 15, 2026: Third installment.
January 15, 2027: Fourth installment.

The IRS generally requires estimated tax payments when both conditions apply:

You expect to owe at least $1,000 after withholding and refundable credits.
Your withholding and refundable credits are less than the smaller of 90% of your expected 2026 tax or 100% of the tax shown on your 2025 return.

Higher-income taxpayers may need to use 110% of the prior-year tax for the safe-harbor calculation. Special rules may apply to farmers, fishers, and taxpayers with uneven income.

Review the official 2026 Form 1040-ES and Publication 505, Tax Withholding and Estimated Tax before calculating the payment.

Connecticut Estimated Tax Is Also Due September 15!

A New Haven business owner may have both federal and Connecticut estimated tax obligations.

The Connecticut Department of Revenue Services (DRS) generally requires estimated payments when a taxpayer expects to owe at least $1,000 in Connecticut income tax after applicable withholding, credits for taxes paid to another jurisdiction, and Connecticut pass-through entity tax credits.

Calendar-year taxpayers generally make Connecticut estimated payments on:

April 15.
June 15.
September 15.
January 15.

Use Form CT-1040ES, Estimated Connecticut Income Tax Payment Coupon for Individuals, when applicable. Payments can be scheduled through the Connecticut DRS myconneCT portal.

Do not assume that a federal estimated payment satisfies your Connecticut obligation. Federal and state payments are separate. Each payment should be scheduled for the correct tax year, taxpayer account, and payment type.

Practical reminder: Complete your federal and Connecticut estimated tax review before September 15. An underpayment may result in an estimated-tax penalty even if the annual return is filed on time.

Confirm Your Third-Quarter Payroll Tax Deposits!

Payroll tax deposits are not the same as payroll tax returns.

If your New Haven business has employees, federal payroll obligations may include:

Federal income tax withholding.
Social Security tax.
Medicare tax.
Additional Medicare Tax, when applicable.
Federal Unemployment Tax Act (FUTA) tax.

The required federal deposit schedule is based on your employer’s assigned status. Most employers follow either a monthly schedule or a semiweekly schedule. A business that accumulates $100,000 or more in employment taxes during a deposit period may become subject to the next-day deposit rule.

Monthly depositors

Monthly depositors generally deposit employment taxes for a month by the 15th day of the following month.

Review your payroll records for every payroll paid in July and August. Confirm that the associated federal deposits were made on time. For September payroll, monitor the applicable October deposit date.

Semiweekly depositors

Semiweekly depositors generally follow this schedule:

Taxes from wages paid Wednesday, Thursday, or Friday are deposited by the following Wednesday.
Taxes from wages paid Saturday, Sunday, Monday, or Tuesday are deposited by the following Friday.

Your payroll provider, bookkeeper, or tax professional should verify the assigned deposit schedule. Do not select a deposit schedule based only on the business’s size or the number of employees.

Federal tax deposits must generally be made electronically through methods such as the Electronic Federal Tax Payment System (EFTPS), the IRS Business Tax Account, or an authorized payroll provider.

Prepare for Form 941 and Form CT-941!

The third quarter covers payroll paid from July 1 through September 30, 2026.

The federal Form 941, Employer’s Quarterly Federal Tax Return, is generally due on the last day of the month following the end of the quarter. The Q3 statutory date is October 31, 2026. Because October 31 falls on a Saturday, the next-business-day rule applies.

The IRS states that employers that timely deposit all required taxes may receive 10 additional calendar days to file Form 941. Confirm the applicable filing date with your payroll professional before relying on this extension.

Connecticut employers generally file Form CT-941, Connecticut Quarterly Reconciliation of Withholding, by the last day of the month following the quarter. For Q3 2026, the normal deadline is October 31, 2026.

Connecticut also requires withholding deposits to be made electronically. Your assigned remitter status may be:

Weekly.
Monthly.
Quarterly.

There is no single September payroll-deposit date that applies to every Connecticut employer. Deposit deadlines depend on your remitter classification and payroll dates.

Use the Connecticut DRS 2026 Withholding Tax Information page to review deposit procedures, electronic filing requirements, and Form CT-941 instructions.

Complete These Year-End Recordkeeping Steps Now!

September is an appropriate time to organize records before the final quarter becomes compressed with payroll, customer activity, and year-end planning.

1. Reconcile business bank accounts

Reconcile every business checking account, savings account, credit card, and payment processor account through August 31.

Identify:

Unrecorded deposits.
Duplicate expenses.
Personal transactions.
Bank fees.
Loan payments.
Merchant processing fees.
Transfers between business accounts.

Do not classify personal spending as a business deduction. Incorrect classifications can distort net profit and increase audit risk.

2. Update your profit-and-loss statement

Prepare a year-to-date profit-and-loss statement through August or the most recent completed month.

Review revenue by source and expenses by category. Compare current results with:

Your 2025 financial statements.
Your original 2026 budget.
Your estimated tax calculation.
Your expected fourth-quarter sales.

Use this information to update your tax strategy. Higher-than-expected income may require an increased September payment or additional withholding. Lower income may justify a revised projection, but payments should not be reduced without a complete calculation.

3. Review deductions and supporting records

Review potentially deductible expenses, including:

Advertising and marketing.
Software and subscriptions.
Professional services.
Business insurance.
Office supplies.
Rent and utilities.
Contract labor.
Business mileage.
Equipment and depreciation.
Retirement contributions.
Qualified health insurance costs.
Home office expenses, when eligible.

Retain invoices, receipts, payment confirmations, mileage logs, and written business purposes. A bank statement alone may not establish the business purpose of an expense.

4. Review equipment and asset purchases

Create a list of equipment, furniture, computers, vehicles, and other business assets purchased during 2026.

Record:

Purchase date.
Vendor.
Cost.
Business-use percentage.
Financing terms.
Date placed in service.
Related invoices and receipts.

Some purchases may qualify for depreciation or other deductions. The appropriate treatment depends on the asset, business use, placed-in-service date, and current tax law.

Do not purchase equipment solely to create a deduction. Evaluate the business need, cash flow, financing cost, and tax treatment together.

5. Prepare for Forms 1099-NEC and 1099-MISC

Review payments to independent contractors and other vendors before December.

Collect completed Form W-9, Request for Taxpayer Identification Number and Certification, from eligible vendors. Confirm the vendor’s legal name, taxpayer identification number, address, and payment records.

The information may be needed for Form 1099-NEC, Nonemployee Compensation, or Form 1099-MISC, Miscellaneous Information. Missing vendor information can delay year-end reporting and may create backup-withholding or information-return issues.

6. Verify payroll and employee records

Review employee names, addresses, Social Security numbers, wage totals, benefits, tips, and withholding records.

Correct payroll discrepancies before year-end. Confirm that payroll reports reconcile to:

General ledger entries.
Payroll bank withdrawals.
Federal deposits.
Connecticut withholding deposits.
Workers’ compensation records.
Employer benefit records.

Accurate records make Forms W-2, Wage and Tax Statement, and Form W-3, Transmittal of Wage and Tax Statements, easier to prepare.

Build a Fourth-Quarter Tax Strategy!

Use September to identify decisions that may affect your 2026 tax liability.

Review:

Expected fourth-quarter revenue.
Planned equipment purchases.
Retirement plan contributions.
Owner compensation and distributions.
Payroll increases or bonuses.
Health insurance costs.
Business-use vehicle activity.
Inventory levels.
Accounts receivable and payable.
Federal and Connecticut estimated payments.

A tax strategy should support the business’s financial objectives. It should not be limited to finding deductions after the year ends.

Business owners should also review entity structure, bookkeeping quality, cash reserves, and projected tax payments. A year-end adjustment may be more effective when planned in advance.

Schedule a New Haven Small Business Tax Review!

Jose’s Tax Service provides professional tax preparation, tax planning, bookkeeping support, and business assistance for New Haven-area businesses and virtual clients.

The business tax preparation service includes guidance regarding business income, deductions, credits, and filing requirements. Virtual appointments are available for business owners outside New Haven through virtual tax services.

Prepare the following documents for your review:

2025 federal and Connecticut tax returns.
Year-to-date profit-and-loss statement.
Business bank and credit card statements.
Estimated payment confirmations.
Payroll reports and deposit confirmations.
Contractor payment records.
Forms W-9 received.
Equipment and asset purchase records.
Mileage and vehicle logs.
Major contract or revenue changes.
Planned fourth-quarter purchases.

Schedule a tax appointment before September 15 to review your estimated payments and year-end tax planning position.

Practical reminder: Pay applicable federal and Connecticut estimated taxes by September 15, 2026. Verify payroll deposits according to your assigned schedule. Prepare Q3 payroll reconciliations for the October 31 filing deadline. Organized records support accurate deductions, stronger tax planning, and fewer filing-season surprises.

Category: Tax Planning | Tags: small business tax, New Haven business, deductions, tax strategy