Worksheet
Estimated tax set-aside worksheet
This worksheet does one thing: it divides a tax amount you already have into equal payments and into a monthly savings figure. It does not estimate your tax. You supply the expected annual amount, taken from a tax professional or from the worksheet in the IRS Form 1040-ES package, and the arithmetic is done on your device.
Worked example (shown when scripts are off): an expected annual amount of $4,000 with nothing paid yet, split into 4 payments, is $4,000 divided by 4, which is $1,000 per payment. Spread over 12 months it is $4,000 divided by 12, which is $333.34 a month, rounded up to the next cent.
Check the due dates
This tool has no due dates in it. Check the due dates for your tax year in the IRS Form 1040-ES instructions. Whether you must pay in installments at all, and how much, is a question for the IRS instructions or a tax professional. This is general information, not tax advice.
The formula
The worksheet uses three lines of arithmetic and no other numbers.
- Still to cover = expected annual amount minus amount already paid or withheld (never below zero).
- Per payment = still to cover divided by the number of payments left.
- Monthly set-aside = still to cover divided by the number of months you will save over.
Results are rounded up to the next cent, so the payments never add up to less than the amount you need to cover. For example, 10 dollars split in 3 gives 3.34, not 3.33.
Where the annual amount comes from
The expected annual amount is the part this tool cannot supply, and it should not be guessed. Two sources exist. A tax professional can estimate it from your income, deductions and credits. The IRS also publishes a worksheet in the Form 1040-ES package, and IRS Publication 505, Tax Withholding and Estimated Tax, explains how to use it. Rates, brackets and thresholds change from year to year, which is why none are built into this page.
What equal payments can and cannot tell you
Equal payments are the simplest way to plan cash flow, but income can be uneven. If you earn more in some parts of the year, a different schedule may fit better, and the IRS instructions describe how the timing is treated. The worksheet also cannot tell you whether paying in installments is required for you, or what happens if a payment is late or short. Those answers depend on your facts and on the rules for your tax year.
Using the monthly figure
The monthly set-aside is a savings habit, not a payment. Moving that amount into a separate account each month means the money is there when a payment is due. If your income changes, ask for a fresh estimate and re-run the worksheet with the new annual amount and the payments still left.
Where this comes from
The structure follows the plain description of estimated tax in IRS Publication 505, Tax Withholding and Estimated Tax, and the Form 1040-ES instructions, which describe paying in installments. The division is ordinary arithmetic, tested with more than 4,000 input combinations. The site owner is not a tax professional and has not used this in a real filing.
Where to get help
- Volunteer Income Tax Assistance (VITA) offers free basic tax help to people who qualify.
- The Taxpayer Advocate Service is an independent organization within the IRS that helps with unresolved tax problems.
- A licensed tax professional can estimate your annual amount and review your whole situation.