An agent who owes estimated taxes generally must make the September 2026 federal payment by September 15. This standard deadline applies to calendar-year Form 1040 filers; qualifying disaster relief can change it. See the IRS’s 2026 tax calendar.

Reconcile commission receipts, deductible expenses, withholding and earlier payments before calculating the installment. Uneven closings may make the annualized-income method useful because it accounts for when income arrives.

Reconcile five records before the September payment

Gather these records now, then close the books through August 31. Keep expected closings in a separate forecast.

• Commission receipts. Match brokerage statements, referral payments and bank deposits. Reconcile gross commission income, broker splits and other deductions with cash received, counting each charge only once.
• Business expenses. Reconcile receipts and card statements for brokerage charges, advertising, MLS dues, software and other costs. Flag personal portions, vehicle records and equipment purchases for review. Deductible expenses must be ordinary and necessary; retain records supporting receipts and expenses. See IRS Publication 583.
• Other return inputs. Gather wages, investment income, expected deductions and credits, and partnership or S corporation income where relevant. Include your spouse’s figures if filing jointly. Pull your 2025 return for its adjusted gross income and tax figures.
• Federal withholding. Record withholding to date and what you expect for the rest of the year, including a spouse’s withholding on a joint return. Keep it separate from estimated payments.
• Earlier payments and credits. List each 2026 estimated payment’s date, amount and confirmation, plus any 2025 overpayment applied to 2026. Compare your records with IRS payment history. The 2026 Form 1040-ES package includes a payment-record table.

For a cash-method business, income generally counts when actually received or made available without substantial restriction. A closing date alone may not establish receipt, and delaying a deposit does not necessarily defer income. Keep evidence of when the commission became available. See the IRS cash-method rules.

Team owners should track payroll and entity obligations separately from their individual estimate in their brokerage operations planning. The IRS tax calendar distinguishes those schedules.

Why a percentage of gross commissions is only a reserve

A fixed savings percentage can help fund payments, but it does not calculate your tax.

Hypothetical example: A sole proprietor receives $20,000 in business revenue and pays $5,000 in fully deductible current business expenses. That leaves $15,000 of business profit before other return adjustments. Saving 25% of the receipt produces a $5,000 reserve; neither the reserve nor the profit is the federal tax bill.

The tax calculation considers other income, deductions, credits, income tax and self-employment tax, then accounts for withholding and payments. Complete the 2026 estimated-tax worksheet before adjusting your reserve.

If you itemize, use the form with the IRS’s February 25, 2026 correction: the state and local tax deduction limit is $40,400 ($20,200 if married filing separately), with reductions above modified adjusted gross income of $505,000 ($252,500 if married filing separately). The correction applies to page 4; the IRS says it will not revise the PDF.

Check the payment threshold and safe harbor

Under the general rule, estimated payments are required if both conditions apply:

1. You expect to owe at least $1,000 for 2026 after withholding and refundable credits.
2. Your expected withholding and refundable credits fall below the smaller of 90% of your 2026 tax or 100% of your 2025 tax.

The prior-year return must cover 12 months. Substitute 110% for 100% if 2025 adjusted gross income exceeded $150,000, or $75,000 if your 2026 filing status is married filing separately. Special rules apply to qualifying farmers and fishers. Use the worksheet’s tax calculation, not last year’s balance due. See Form 1040-ES, page 1.

These payment targets, often called safe harbors, address underpayment penalties. They do not cap your final tax bill; the Form 1040-ES worksheet cautions that a balance may remain. Timing also matters: reaching the annual target late may still leave an installment penalty, as the IRS installment-payment guidance explains.

Compare regular and annualized installments

The regular installment method generally spreads the annual estimated payment amount across four installments when payments begin in April. When refiguring your estimate during the year, use Worksheet 2-12, “Amended Estimated Tax Worksheet,” on page 26 of 2026 Publication 505 to work out the next required payment.

The annualized-income installment method calculates required payments as income accumulates. It may support smaller early installments when commissions arrive later, but requires more detailed records and calculations. The IRS explains the distinction in Notice 2026-3.

Suppose you had little spring income and a large August commission. Annualization may support smaller spring installments, while the August receipt increases the September calculation.

Use Worksheet 2-9, “2026 Annualized Estimated Tax Worksheet,” in Publication 505, dated March 31, 2026. First complete Worksheet 2-1 through line 14b. Self-employed filers complete Worksheet 2-9’s Section B for self-employment tax before Section A.

These periods are cumulative: September’s column C covers January through August. It multiplies period adjusted gross income by 1.5 before deductions, tax and credits are calculated. Follow the worksheet through its withholding and prior-payment adjustments to line 32. See Publication 505, pages 27–28 and 40–41.

If you use annualization, file Form 2210, including Schedule AI, with your 2026 return, even if no penalty is owed. For the payment you are preparing now, use the 2026 worksheets above. See Form 1040-ES, page 5.

Set the calculation and payment checkpoints

Add these checkpoints to your agent business planning:

• After August 31: Finalize receipts and expenses, update the full-year forecast and compare the regular and annualized calculations. Ask a CPA or enrolled agent to review the choice if income timing or your entity structure complicates it.
• Before September 15: Check state requirements with your state revenue department. For federal disaster relief, confirm the notice’s covered taxpayers, payment types and postponement period. The IRS’s June 16 relief notice for the San Carlos Apache Tribe illustrates how specific eligibility can be. Verify state relief separately.
• By the applicable deadline: Make the payment for tax year 2026 and save confirmation with your completed worksheets. Form 1040-ES lists payment options, including IRS Direct Pay.
• During the fall: Revisit the forecast after significant closings and prepare for the standard January 15, 2027 installment date.