How the Plan Is Calculated
- Profit so far. Income received through the end of the period, minus the standard mileage deduction for the miles driven through that date.
- Projection to a full year. Year-to-date profit is multiplied by 4 after March, 2.4 after May, 1.5 after August, and 1 after December. These are the annualization amounts in IRS Publication 505.
- Tax on the projection. Self-employment tax and federal income tax are calculated on the projected profit, the same way the 1099 tax calculator does it.
- Suggested installment. The planner aims to have one quarter of that tax paid after the first period, half after the second, three quarters after the third, and all of it after the fourth. Each installment is that target minus the installments before it.
- Payments already made. Whatever you have paid toward 2026 is applied to the earliest suggested installments first for planning purposes, and the "still to pay" column shows the remaining balance. The planner does not track actual payment dates or determine whether earlier payments were on time.
The installments are an approximation, not the amounts the IRS requires. The official worksheet in Publication 505 uses 22.5%, 45%, 67.5%, and 90% of the tax on annualized income, compares the result with the regular installment, and applies other adjustments. The planner uses 25%, 50%, 75%, and 100% so that the plan covers the whole estimated tax by the January due date.
When profit is the same every month, the four installments come out equal. When profit rises during the year, they follow your earnings and add up to the tax on the profit you actually made. When profit falls after a strong start, the early installments were based on a higher projection, so together they can exceed the tax for the year; the planner reports that excess and never shows more left to pay than the yearly tax.
Worked Example: A Slow Start and a Busy Fall
A single filer with no other income earns $39,000 in 2026 after expenses other than mileage, more than half of it after September 1, and has made no payments yet. The planner returns:
| Payment period | Income | Mileage deduction | Suggested installment | Four equal payments |
|---|---|---|---|---|
| January 1 – March 31Due April 15, 2026 | $6,000.00 | $2,175.00 | $540.46 | $1,034.80 |
| April 1 – May 31Due June 15, 2026 | $4,000.00 | $1,450.00 | $540.45 | $1,034.80 |
| June 1 – August 31Due September 15, 2026 | $9,000.00 | $3,367.50 | $866.10 | $1,034.80 |
| September 1 – December 31Due January 15, 2027 | $20,000.00 | $6,840.00 | $2,192.20 | $1,034.81 |
| 2026 total | $39,000.00 | $13,832.50 | $4,139.21 | $4,139.21 |
Both columns reach the same total in this example, because profit rose during the year. The difference is timing: four equal payments would ask this driver for $1,034.80 in April, before most of the year's income existed, while the planner suggests $540.46 then and most of the tax in January, after the busy season.
What the IRS Says About Uneven Income
IRS Publication 505 describes two ways to figure each payment. The regular installment method divides the annual estimated tax by four, and the publication says to use it only if your income is basically the same throughout the year. For income that does not arrive evenly, it describes the annualized income installment method, under which the required payments may not be the same for each period.
The publication also notes that the underpayment penalty is figured separately for each payment period, which is why the timing of payments matters and not only the yearly total. This planner borrows the publication's annualization amounts to spread payments in line with income, but it uses its own percentages, described above. It does not fill in the IRS worksheet for you and does not test whether a penalty applies, so its installments can differ from the amounts the worksheet gives.
If you use the IRS annualized income installment method to figure your estimated payments, Publication 505 says you must file Form 2210 with your 2026 tax return. See Schedule AI in the Form 2210 instructions. This planner does not complete those forms.
Source: IRS Publication 505, Tax Withholding and Estimated Tax. For the rules in plain language, read the guide to quarterly tax payments for gig workers.
2026 Estimated Tax Due Dates
Estimated payments for 2026 are due April 15, June 15, and September 15, 2026, and January 15, 2027. The guide to quarterly tax payments explains who has to pay, which months each date covers, and how to pay.
Never miss a payment. Add the next 4 due dates (Jan 15, 2027 – Sep 15, 2027) to Google Calendar, Apple Calendar, or Outlook, with a reminder 3 days before each one.
Add to calendarWhat the Planner Leaves Out
- State and local estimated taxes.
- Other household income, a W-2 job, and tax withheld from a paycheck.
- Business expenses other than mileage, such as platform fees and the business share of a phone plan. Subtract them yourself and enter the income that is left.
- The IRS worksheet percentages, limits, and comparisons with the regular installment.
- Tax credits and the qualified tips deduction.
- The Social Security wage base and Additional Medicare Tax, which only affect high profits.
- Safe-harbor and underpayment-penalty calculations.
Estimated Tax Planner FAQs
Do the four estimated payments have to be equal?
Not always. IRS Publication 505 describes dividing the annual estimated tax by four as the regular installment method and says to use it only if your income is basically the same throughout the year. If you do not receive income evenly, your required payments may not be the same for each period.
Why does the June–August period ask for miles twice?
The IRS business mileage rate changed on July 1, 2026. Miles driven in June use 72.5 cents per mile and miles driven in July and August use 76 cents, so the planner needs them separately.
I already made some payments this year. How do I use the planner?
Enter the total you have paid toward 2026 in the field for payments already made. For planning purposes, the planner applies it to the earliest suggested installments first and shows the remaining balance. It does not track actual payment dates. A late payment does not automatically eliminate an underpayment penalty for an earlier period.
Who has to make estimated tax payments?
In most cases you must pay estimated tax for 2026 if you expect to owe at least $1,000 after subtracting withholding and tax credits, and your withholding and credits will not cover the amount the IRS requires. Drivers paid on a 1099 usually have no withholding.
Tax Information Disclaimer
The quarterly tax calculator and this page are general education, not tax, legal, or accounting advice. Tax rules change and depend on your circumstances; consult a qualified tax professional before filing. See our terms of use.