51: Estimated Payment of Individual Income Tax 2024 (2024)
Idaho · Idaho Tax Commission · Used for tax years 2024
Idaho Form 51 is a payment voucher for individual income tax. It includes a worksheet to calculate any payment due for a valid 2024 filing extension and can also be used for 2025 estimated tax payments or Qualified Investment Exemption (QIE) recapture payments.
Who files this form
Use Form 51 to:
- Calculate any payment needed for a valid filing extension for tax year 2024.
- Make estimated payments for tax year 2025, checking the appropriate year on the voucher.
- Pay Qualified Investment Exemption (QIE) recapture when you don’t file your income tax return by the due date.
For a 2024 filing extension, you must pay at least 100% of the income tax on your 2023 return or 80% of the estimated tax due on your 2024 return. You can’t use the 2023 tax method if you’ve never filed in Idaho. Use the worksheet to calculate any payment still due. If that amount is $50 or less, you don’t have to pay it now to get the extension.
Return the voucher only if you’re making a payment.
When it's due
- April 15, 2025, for tax year 2024: The regular filing deadline. Pay any required extension payment online or have it postmarked by this date. If the worksheet payment due is $50 or less, you don’t have to pay it now to get the extension.
- October 15, 2025, for tax year 2024: If you qualify for the extension, file and pay by this date.
An extension gives you more time to file, not more time to pay. Interest applies to any tax due that you don’t pay by April 15, 2025. Penalties can also apply.
What you'll need
Have these records and details ready:
- Your 2023 Idaho Form 40 or Form 43, if you filed, for the prior-year tax calculation.
- Your estimated 2024 taxable income, additional income taxes, and income tax credits.
- Your 2024 Idaho income tax withholding and Form 51 payments for 2024.
- Your name, full Social Security number, and mailing address. For a joint return, include your spouse’s name and full Social Security number.
- The tax year and payment amount for the voucher.
Keep the completed Tax Payment Worksheet for your records.
How to file
For a 2024 extension payment, complete the Tax Payment Worksheet. Line 11 shows the minimum payment needed for a valid extension. You may enter an additional payment on line 12 to reduce tax owed and the interest it will accrue. Add lines 11 and 12, then enter the total on line 13 and the voucher.
The form allows the required extension payment to be paid online or mailed. For a mailed payment, return just the voucher to:
Idaho State Tax Commission
PO Box 83784
Boise ID 83707-3784
Check the appropriate tax year on the voucher. Keep the worksheet, and return the voucher only if you’re making a payment.
For a QIE recapture payment, write “Payment of QIE Recapture” at the bottom of the voucher and return it with a check.
Common mistakes
- Treating a filing extension as extra time to pay. Interest applies to unpaid tax after April 15, 2025, for tax year 2024, and penalties can apply.
- Using the prior-year tax method when you’ve never filed in Idaho. The form says you can’t use that method in this situation.
- Entering a negative payment due. Enter “0” on worksheet line 11 if line 7 minus line 10 is negative.
- Sending the worksheet or a voucher without a payment. Keep the worksheet and return only the voucher, and only when making a payment.
- Not checking the appropriate tax year. The voucher includes 2024 and 2025 choices.
- Leaving off the QIE recapture label. Write “Payment of QIE Recapture” at the bottom of the voucher and return it with a check.
Questions people ask
Do I need to pay if my extension payment is $50 or less?
No. If the worksheet’s payment due is $50 or less, you don’t have to pay it now to get the extension. Interest still applies to any tax due that remains unpaid after April 15, 2025, for tax year 2024.
What if I didn’t file a 2023 tax return?
Enter the amount from worksheet line 6 on line 7. Line 6 is 80% of the amount on line 5.
Can I pay more than the minimum extension amount?
Yes. Enter any additional amount on line 12 to reduce the tax you owe and the interest it will accrue. Add it to line 11 and put the total on line 13 and the voucher.
Can I use this form for 2025 estimated payments?
Yes. The form allows estimated payments for tax year 2025. Check the appropriate year on the voucher.
Should I mail the worksheet with my payment?
No. Keep the worksheet for your records. Return just the voucher, and only if you’re making a payment.