What is Idaho's income tax rate for self-employed workers in 2026?

A flat 5.3% on taxable income above a small zero bracket. After deductions and the zero bracket, most gig workers pay an effective Idaho rate around 4.5% to 5%.

Do Boise or Meridian tax self-employment income?

No. No Idaho city or county has a local income tax, so Form 40 is the only state income return.

When are Idaho estimated taxes due?

Form 51 payments are due April 15, June 15, September 15, 2026 and January 15, 2027.

What is the $10 Permanent Building Fund tax?

A flat $10 Idaho adds to most individual returns to fund state buildings. It is owed regardless of income unless you receive public assistance.

How much should an Idaho gig worker set aside?

About 26% to 30% of net profit covers the 15.3% SE tax, federal income tax and Idaho's 5.3% flat tax.

Idaho Self-Employed Tax Calculator

Federal income tax + 15.3% self-employment tax + Idaho state tax (5.3% flat) on 2026 1099 income.

Idaho cut its rate to a flat 5.3% and quietly kept a $10 surcharge on every return. Idaho taxes self-employment profit at a single flat 5.3% rate on income above a small zero-bracket amount, after the 2025 cut from 5.695%. No Idaho city or county levies an income tax, but every return also owes the flat $10 Permanent Building Fund tax.

Self-employed income & expenses

Estimate federal + SE + state tax for the 2026 tax year in one pass.

Annual 1099 income

Business miles driven

Other business expenses

Self-employed health insurance

Retirement contributions (SEP / Solo 401k)

W-2 income (if any)

Federal tax withheld

Filing status

State

Estimated total tax bill

$12,499

Refund / owed

-$12,499

Effective rate

20.8%

Detailed breakdown

Mileage deduction$6,080

Total business expenses$8,580

Net self-employment income$51,420

Self-employment tax (15.3%)$7,265

½ SE deduction (above-the-line)$3,633

Adjusted gross income$47,787

Taxable income$31,687

Federal income tax$3,554

State tax (est.)$1,679

Quarterly estimated payment$2,938

Marginal rate17.3%

Idaho city tax rates for self-employed workers (2026)

Idaho taxes self-employment profit at a single flat 5.3% rate on income above a small zero-bracket amount, after the 2025 cut from 5.695%. No Idaho city or county levies an income tax, but every return also owes the flat $10 Permanent Building Fund tax.

Local and state tax rates for self-employed residents of major Idaho cities in 2026
City	Local rate	State rate	What gig workers should know
Boise	No city income tax	Up to 5.3%	Largest market; state return only.
Meridian	No city income tax	Up to 5.3%	Fast-growing suburb; no local income levy.
Nampa	No city income tax	Up to 5.3%	State-only income filing.
Idaho Falls	No city income tax	Up to 5.3%	State-only income filing.
Coeur d'Alene	No city income tax	Up to 5.3%	Washington-border drivers: see filing notes.

Idaho local and state filing deadlines

Q1 Form 51April 15, 2026
Idaho charges underpayment penalties if you skip estimates and owe at filing.
Q2 Form 51June 15, 2026
Second installment.
Q3 Form 51September 15, 2026
Third installment.
Q4 Form 51January 15, 2027
Final installment for 2026.
Idaho Form 40 returnApril 15, 2027
Resident return plus the $10 Permanent Building Fund tax.
Q1 federal 1040-ESApril 15, 2026
Covers income earned January 1 – March 31.
Q2 federal 1040-ESJune 15, 2026
Covers April 1 – May 31.
Q3 federal 1040-ESSeptember 15, 2026
Covers June 1 – August 31.
Q4 federal 1040-ESJanuary 15, 2027
Covers September 1 – December 31.

Idaho's flat 5.3% applies after a zero bracket (roughly the first $4,800 single / $9,600 joint), so the effective rate on typical gig profit is closer to 4.5%–5%.
Every Idaho return owes the flat $10 Permanent Building Fund tax unless you receive public assistance — small, but it surprises first-time filers.
Coeur d'Alene and Post Falls residents who gig across the Washington line still owe Idaho tax on all of it; Washington has no income tax to credit.

See every Idaho tax form you need to file — annual, quarterly, and local →

Frequently asked questions

What is Idaho's income tax rate for self-employed workers in 2026?: A flat 5.3% on taxable income above a small zero bracket. After deductions and the zero bracket, most gig workers pay an effective Idaho rate around 4.5% to 5%.
Do Boise or Meridian tax self-employment income?: No. No Idaho city or county has a local income tax, so Form 40 is the only state income return.
When are Idaho estimated taxes due?: Form 51 payments are due April 15, June 15, September 15, 2026 and January 15, 2027.
What is the $10 Permanent Building Fund tax?: A flat $10 Idaho adds to most individual returns to fund state buildings. It is owed regardless of income unless you receive public assistance.
How much should an Idaho gig worker set aside?: About 26% to 30% of net profit covers the 15.3% SE tax, federal income tax and Idaho's 5.3% flat tax.