Idaho: corporate income tax, franchise tax unconfirmed and an annual report required.
Each fact below cites the agency page we read and the day we read it. Where a rule is still being confirmed, the page says so instead of showing a zero.
Verified facts
Corporate income tax
Yes
Corporation income tax, Form 41; rate 5.3% for tax year 2025 (agency rate history: 5.695% in 2024, 5.8% in 2023). Rate is on taxable income; no 2026 rate listed on the retrieved page.
Franchise or privilege
Not verified
Yes - franchise tax on corporations for the privilege of doing business in Idaho, at the same rate as the business income tax; a corporation is not subject to both the franchise tax and the income tax (Idaho Code 63-3025A).
Not verifiedEntity annual report
Yes
Annual report required, filed with the Secretary of State each year before the end of the month in which the entity's public organic record became effective (anniversary month); from the first anniversary it must be received by close of…
Return due date
Published rule
Return due the 15th day of the fourth month after the close of the tax year (April 15 for calendar year); next business day if a weekend or legal holiday. Same formula for fiscal years. Payment is due the same date - Idaho says there are no extensions allowing late payment and charges interest after the original due…
Extension
Not verified
6-month extension to file with a valid extension (Form 41ES worksheet); it does NOT extend the time to pay - "There aren't any extensions allowing you to pay late." Interest runs from the original due date.
Not verifiedZero activity / minimum tax
Not verified
Not verified
Long-form guide in professional review
Dates, extensions and payments
Filing and payment dates stay separate wherever the source supports it.
- Filing
Return filing
Return due the 15th day of the fourth month after the close of the tax year (April 15 for calendar year); next business day if a weekend or legal holiday. Same formula for fiscal years. Payment is due the same date - Idaho says there are no extensions allowing late payment and charges interest after the original due…
- Entity report
Entity report
Annual report required, filed with the Secretary of State each year before the end of the month in which the entity's public organic record became effective (anniversary month); from the first anniversary it must be received by close of…
Email me the Idaho guide
We send you this page with its sources, and we tell you if a date changes.
Frequently asked questions
Does Idaho impose a corporate income tax?
Yes. The state agency publishes the applicable rate.
When is the Idaho corporate return due?
Return due the 15th day of the fourth month after the close of the tax year (April 15 for calendar year); next business day if a weekend or legal holiday. Same formula for fiscal years. Payment is due the same date - Idaho says there are no extensions allowing late payment and charges interest after the original due…
Does an extension also postpone the tax payment?
No. The extension moves the filing date, not the payment date; unpaid tax can accrue penalty and interest.
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