Idaho business tax deadlines
State-specific deadlines for Idaho businesses — income tax, payroll, sales tax, and entity returns — alongside the federal calendar.
Idaho's state income tax is a flat 5.8% (effective tax year 2023) for both individuals and corporations. Sales tax is 6%. Idaho filing dates align with federal April 15 and October 15 extended. Quarterly estimated taxes match the federal schedule.
Idaho-specific deadlines
April 15
StateIdaho Individual & Business Returns
Form 40 (individual), Form 41 (corporation), Form 41S (S-Corp) due. Extension to October 15 available.
Quarterly
StateIdaho Estimated Taxes
April 15, June 16, September 15, January 15.
Monthly / Quarterly
StateIdaho Sales Tax (Form 850)
Filing frequency depends on volume: monthly (large), quarterly (medium), or annually (small). Returns due the 20th of the month following the period.
Quarterly
PayrollIdaho Withholding (Form 967)
Quarterly withholding return due the last day of the month following the quarter.
Federal deadlines (also apply in Idaho)
January 15
FederalQ4 Estimated Tax Payment
Final estimated tax payment for the prior tax year (individuals, sole props, S-Corp owners).
January 31
PayrollW-2s & 1099-NEC Due
W-2s to employees, 1099-NEC to contractors and the IRS, 941 for Q4 of prior year.
February 28
InformationPaper 1099 Filings
Deadline for paper 1099 filings to the IRS (March 31 if filing electronically).
March 15
FederalS-Corp & Partnership Returns
Form 1120-S (S-Corp) and Form 1065 (Partnership) due. Extension to September 15 available via Form 7004. Also: S-Corp election (Form 2553) deadline for current tax year.
April 15
FederalIndividual & C-Corp Returns + Q1 Estimated Tax
Form 1040 (individuals, sole props with Schedule C), Form 1120 (C-Corp), and Q1 estimated tax payment. Extension via Form 4868 (individuals) or Form 7004 (corps) — extends filing, NOT payment.
April 30
PayrollQ1 Form 941
Quarterly federal payroll tax return for the January–March quarter.
June 16
FederalQ2 Estimated Tax
Second-quarter estimated tax payment for the current tax year.
July 31
PayrollQ2 Form 941
Quarterly federal payroll tax return for the April–June quarter.
September 15
FederalQ3 Estimated Tax + Extended S-Corp/Partnership
Third-quarter estimated tax payment AND extended S-Corp and Partnership returns due.
October 15
FederalExtended Individual & C-Corp Returns
Final deadline for extended Form 1040 and Form 1120 returns. No further extensions.
October 31
PayrollQ3 Form 941
Quarterly federal payroll tax return for the July–September quarter.
December 31
InformationYear-End Planning Deadline
Last day for owner draws, retirement contributions to apply to current tax year, Section 179 equipment placed in service, and most year-end tax moves.
Other state calendars
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