Before you start

An SSN or ITIN
Form W-4 with your employer for federal withholding, and Idaho Form ID W-4 for state withholding
Records of foreign income and foreign financial accounts
Receipts for grocery sales tax, if you intend to claim the actual amount rather than the flat credit

Step-by-step

1
Complete the W-4 and the Idaho ID W-4 on day one
Idaho has its own withholding certificate alongside the federal W-4. With a single flat rate the state calculation is simple; getting the federal form wrong remains the commonest cause of an April surprise.
Via employerWho: YouFirst week of employment
2
Determine your US tax residency
The substantial presence test counts weighted days over three years to decide whether the US taxes your worldwide income or only US-source income. Your visa category does not decide this.
OnlineWho: You
3
Check for an applicable tax treaty
The US has treaties with around 70 countries that can reduce or exempt tax on particular income. Idaho begins from federal taxable income, so a federal treaty exclusion generally carries through to the state return.
OnlineWho: You
4
File federal and Idaho returns by 15 April
The tax year is the calendar year and both returns are due on the same date, which is simpler than Virginia's 1 May split. With a flat rate the Idaho return is among the shortest state returns in the country.
OnlineWho: YouBy 15 April annually
5
Claim the grocery credit — you only get it by filing
Idaho taxes food at the full 6% and refunds part of it through a credit on the income tax return, currently $155 per person. Alternatively you can keep receipts and claim the actual sales tax paid on food, up to a higher cap. People who owe no Idaho tax sometimes skip filing and forfeit it.
OnlineWho: YouWith the annual return
6
File an FBAR if foreign accounts exceed $10,000
Aggregate foreign account balances over $10,000 at any point in the year trigger a FinCEN filing, separate from and additional to your tax return.
OnlineWho: You

Documents you’ll need

Form W-2 from each employer, issued by 31 January
Form 1099s for freelance, interest and investment income
Passport and travel history for the substantial presence day count
Grocery receipts, if claiming actual food sales tax rather than the flat credit
Foreign account statements for FBAR reporting

Things most newcomers don’t know

Idaho went flat, and the rate is 5.3%.

Idaho replaced its graduated schedule with a single rate and House Bill 40, signed in 2025, cut that rate to 5.3% — described by the governor's office at the time as the largest income tax cut in state history, returning about $253 million. The Tax Commission's 2026 withholding guidance applies 5.3% to supplemental payments, confirming the rate carried into the current year.

Source: Idaho State Tax Commission — individual income tax rate schedule

No Idaho city or county may levy an income tax.

A Boise payslip has one state line and nothing municipal. That is a genuine structural difference from Kentucky, where Lexington layers 2.25% plus a 0.5% school levy on top of the state rate, or from Ohio and Michigan where the local tax follows your workplace. When comparing a Boise offer with a midwestern one, compare the total wage tax, not the state rate.

Source: Idaho State Tax Commission — individual income tax rate schedule

Idaho taxes groceries, and then hands some of it back — if you file.

Most states exempt food from sales tax; Idaho charges the full 6% and rebates it through a credit on the income tax return, currently $155 per person, with an option to claim the actual tax paid on receipts up to a higher cap instead. The credit exists only for people who file, so a year with no Idaho liability is still a year worth filing.

Source: Idaho State Tax Commission — individual income tax rate schedule

Your visa does not determine your tax residency.

The substantial presence test — a weighted day count across three years — decides whether the US taxes your worldwide income. Someone on a temporary visa can be a US tax resident; someone on a long visa can fail the test.

Source: IRS — substantial presence test

Common mistakes to avoid

Not filing an Idaho return in a year you owe nothing, and forfeiting the grocery credit.
Comparing Idaho's 5.3% against a state headline rate that excludes a local wage tax.
Assuming groceries are untaxed, as they are in most states.
Assuming your visa type settles your tax residency.
Missing the FBAR because a home-country account did not feel 'foreign'.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.