41ES: Estimated Tax Payment/Extension of Time Payment Business Income Tax and Instructions 2025 (2025)
Idaho · Idaho Tax Commission · Used for tax years 2025
Idaho Form 41ES includes worksheets and a payment voucher for 2025 business income tax estimated payments and extension-of-time payments. The worksheets calculate payment amounts, and the voucher identifies the business, tax period, and amount paid.
Who files this form
For tax year 2025, a corporation must make Idaho estimated tax payments if both apply:
- It is required to make estimated tax payments to the IRS.
- It expects an Idaho income tax liability of $500 or more.
Estimated payments are not required if the corporation was not required to file an Idaho return for the previous tax year. They also are not required on tax due on income reported for individual shareholders.
S corporations compute estimated payments on Idaho tax due on net recognized built-in gains and excess net passive income.
Businesses can also use Form 41ES to make an extension-of-time payment. Use Part B to determine whether a payment is needed.
When it's due
- 2025 calendar-year estimated payments: Due April 15, June 15, September 15, and December 15, 2025.
- Fiscal-year estimated payments for the 2025 form: Due on the 15th day of the 4th, 6th, 9th, and 12th months of the tax year.
- Weekend or legal holiday: If a payment deadline falls on a Saturday, Sunday, or legal holiday, payment is due the next regular business day.
- Short tax year: If the short tax year ends before any remaining due dates, the final estimated payment is due by the 15th day of its last month. No estimated payment is required if the short year is less than four months or the payment requirements were not met before the first day of its last month.
- 2025 extension payment: The instructions say to pay online or mail payment by April 15 to avoid a penalty. They do not specify the calendar year for that April 15 date.
What you'll need
Have the following information available to complete the worksheets and voucher:
- Business name, EIN, current mailing address, and calendar-year or fiscal-year information.
- Your 2024 tax return, if filed, for the prior-year tax comparison.
- Estimated 2025 Idaho taxable income, income tax credits, and applicable credit recapture amounts.
- Amounts of estimated and tentative payments already made.
- ABE tax paid by another entity from Form 41S, line 61, or Form 65, line 57, if applicable.
Use personalized Form 41EST vouchers if you received them. Otherwise, use Form 41ES.
If using Form 41ES to pay qualified investment exemption (QIE) recapture when filing after the return's due date, include a copy of Form 49ER.
How to file
- Complete the appropriate worksheet. Use Part A for estimated payments or Part B for an extension payment.
- For estimated payments, each payment is 25% of the smaller of 100% of the corporation's 2024 income tax or 90% of its 2025 income tax, using the worksheet's adjustments.
- For an extension payment, Part B compares prior-year tax with 80% of estimated 2025 tax, then subtracts applicable payments. If the resulting amount is $50 or less, no payment is required.
Pay online: Visit tax.idaho.gov/epay. Do not send a voucher with an online payment.
Pay by mail: Use the voucher when sending a check and/or money order. Mail to:
Idaho State Tax Commission
PO Box 83784
Boise ID 83707-3784
Common mistakes
- Using the wrong form for an ABE election payment. For an Affected Business Entity Election payment made before filing a return, use Form ABE-ES.
- Sending a voucher after paying online. The form says not to send one.
- Leaving incorrect preprinted information unchanged. Cross it out, enter the correct information, and check the mailing-address change box if your mailing address changed.
- Not updating remaining estimated payments. If payments are based on 90% of current-year tax and your anticipated tax changes, recompute the remaining payments.
- Treating the filing extension as permission to leave tax unpaid. Paying less than the required extension amount results in a penalty. A penalty also applies if you pay the required amount but do not pay the remaining tax by the extended due date. Interest accrues on unpaid tax.
Questions people ask
Do I need to request a filing extension in writing?
No. The instructions allow an automatic six-month extension without a written request. To qualify, pay at least 80% of the 2025 income tax liability or 100% of the total income tax reported on the 2024 return. If the amount owed is $50 or less, no payment is required, but interest accrues.
What happens if I underpay estimated tax?
Interest is due on the difference between the required payment and the amount paid. It runs from the installment's due date until the required amount is paid or the return's due date, whichever comes first. Use Form 41ESR to determine underpayments and interest. The stated interest rate is 6% for both 2025 and 2026.
What happens if I pay too much?
You can receive a refund after filing your return or designate all or part of the excess for next year's estimated tax on Form 41 or Form 41S. Overpayments are applied to prior-year tax debt before refunds or carryovers are allowed.
Can I use the annualized income method?
Yes, if your federal estimated payments are based on annualized income, you can use that same method for Idaho estimated payments.