United States · Self-employed · Uneven income
Annualized income installment method calculator.
For freelancers, creators and seasonal businesses whose profit arrives late in the year. Enter running profit totals and compare the Schedule AI installments with four equal payments. Runs in your browser.
A single filer with $4,000, $9,000, $22,000 and $60,000 of cumulative profit by March, May, August and December would owe $508.66 by April 15 under this model, against $2,922.54 with equal payments. Enter your own running totals below.
How this is calculated
- Annualize each period. Cumulative profit through March 31, May 31, August 31 and December 31 is multiplied by 4, 2.4, 1.5 and 1 (Publication 505, Worksheet 2-9).
- Tax on the annualized profit. Self-employment tax is 15.3% of 92.35% of profit (Social Security stops at $184,500), half of it is deducted, then the 2026 standard deduction and brackets apply to the rest.
- Apply the percentages. Required cumulative payments are 22.5%, 45%, 67.5% and 90% of that annualized tax.
- Compare with the regular installment. Each annualized installment is capped by 25% of the required annual payment plus any shortfall carried forward, the smaller-of rule on lines 25 to 29 of the worksheet.
- Required annual payment is the smaller of 90% of the full-year tax in the model and your prior-year amount (100%, or 110% when prior-year AGI is above $150,000), if you enter one.
Worked example: single filer, $4,000 / $9,000 / $22,000 / $60,000 cumulative profit
| Line | Apr 15 / Jun 15 / Sep 15 / Jan 15 |
|---|---|
| Annualized profit (x4, x2.4, x1.5, x1) | $16,000 / $21,600 / $33,000 / $60,000 |
| Annualized total tax (SE + income tax) | $2,261 / $3,449 / $6,163 / $12,989 |
| Cumulative required (22.5/45/67.5/90%) | $509 / $1,552 / $4,160 / $11,690 |
| Annualized installment due on each date | $509 / $1,044 / $2,608 / $7,530 |
| Equal installments (25% of $11,690) | $2,923 / $2,923 / $2,923 / $2,923 |
In this example the model asks for $509 by April 15 rather than $2,923, but the same total ($11,690) by January 15. The annualized method shifts when money is due; it does not reduce the year's required payments.
What this does not cover
- The penalty itself or Form 2210. Use the underpayment penalty calculator for that.
- W-2 wages, withholding (which counts as paid evenly unless you elect otherwise), interest, dividends and capital gains.
- The qualified business income deduction, itemized deductions, credits, the Additional Medicare Tax interaction with wages and any state tax. Ignoring the QBI deduction makes the modelled tax higher than it may be.
- Farmers and fishers, nonresident aliens, married couples with income on both sides, and the 2025 Form 2210 rules.
- Whether you should use this method. It is a modelling aid, not advice.
Method and assumptions
Profit is entered as running totals because Schedule AI annualizes income through the end of each period. The model uses the single-source self-employment profit you type and nothing else, so it is a floor for comparison, not a return. The 2026 brackets and standard deduction come from the same table the other TNAADO US tax tools use.
Results vary with your actual income, deductions, credits and filing situation. This page uses the figures you enter and published IRS rules; it does not predict what you will earn or owe. This is general information, not tax, legal or accounting advice; confirm your own situation against the linked IRS instructions or with a qualified preparer. Nothing here collects or stores personal data.
Sources
- IRS Publication 505, Tax Withholding and Estimated Tax (2026), retrieved October 2026
- IRS Instructions for Form 2210 (Schedule AI, annualized income installment method), retrieved October 2026
- IRS: Self-employment tax (Social Security and Medicare taxes), retrieved October 2026
- IRS Topic no. 751, Social Security and Medicare withholding rates ($184,500 wage base for 2026), retrieved October 2026
- IRS Rev. Proc. 2025-32 (2026 brackets, standard deduction, section 199A thresholds, $400 minimum QBI deduction), retrieved October 2026
Cite this page: TNAADO Tools, "Annualized income installment method calculator," tools.tnaado.ca/us/annualized-income-installment-method-calculator/, figures retrieved October 2026.
Frequently asked questions
What is the annualized income installment method?
It is a way to figure each required estimated tax installment from the income you actually earned up to that date instead of assuming four equal quarters. Publication 505 explains it in Worksheet 2-9, and you report it on Form 2210, Schedule AI.
Who benefits from the annualized method?
People whose profit arrives late in the year, such as seasonal businesses or creators with a big payout in the fall. If your income is steady, the regular equal installments are usually simpler and the two methods give similar answers.
What are the annualization factors?
For the four periods ending March 31, May 31, August 31 and December 31 the amounts are 4, 2.4, 1.5 and 1, and the applicable percentages of annualized tax are 22.5%, 45%, 67.5% and 90%, per Publication 505, Worksheet 2-9.
Does this reduce my tax for the year?
No. It changes how much must be paid by each date to avoid an underpayment penalty. The total tax for the year is the same.
Is this a prediction of what I will owe?
No. It runs your own figures through published IRS rules for a self-employment-only situation. Results vary with real income, deductions, credits and state tax.
Not tax advice
This is an educational estimate built from the numbers you enter and published IRS rules. It is not tax advice and does not predict what you will earn or owe. Self-employed in Canada instead? Use the Canadian self-employment tax calculator.