Idaho Income Tax Calculator 2026

How Idaho taxes income

Idaho uses a single flat rate of 5.30%. Whether you earn $40,000 or $400,000, every dollar of taxable income is taxed at the same percentage. There are no brackets to climb and no threshold to cross.

Before that rate is applied, Idaho subtracts a standard deduction of $16,100 for a single filer and $32,200 for a couple filing jointly.

A flat rate is simpler to predict than a bracketed one, but it is not automatically cheaper. On $85,000, Idaho takes $3,652 — which puts it 37th out of 51 for state income tax at that salary.

How Idaho compares to the other 50

On $85,000, a single filer pays $3,652 in Idaho state income tax. That ranks 37th out of 51 — toward the expensive end.

For scale: 9 states charge nothing at all, and at the other end Oregon takes $6,604 on the same salary.

Income tax is only one of the three big state taxes, though. A state with no income tax often has higher property tax, and a state with high income tax may have low property tax. Ranking states on this one number alone is the most common mistake in these comparisons.

What filing status changes in Idaho

On the same $85,000 salary, the four filing statuses do not produce the same bill. Filing single costs $20,024 in total tax; filing jointly costs $15,141, $4,883 less.

Most of that difference is federal. Idaho's flat 5.30% rate does not change with filing status, though the deduction and exemptions it allows do.

Head of household sits between the two at $17,102, and married filing separately at $20,024. Filing separately is almost never cheaper, but it exists for situations where the tax is not the deciding factor.

What $85,000 looks like in each paycheck

Annual figures are how tax is calculated, but not how anyone experiences it. Spread across the year, $85,000 in Idaho comes to $2,499 every two weeks after federal tax, FICA and Idaho state tax — from a gross of $3,269.

Paid monthly, that is $5,415 landing in your account against $7,083 gross. Paid weekly, $1,250 out of $1,635.

Your actual paycheck will differ from these because employers withhold on a schedule set by your W-4, not on your final tax bill. Over-withholding produces a refund; under-withholding produces a bill in April. Neither changes what you owe.

How to pay less tax in Idaho

The largest lever available to most employees is pre-tax retirement contributions. Putting $5,000 into a traditional 401(k) cuts the $85,000 bill by $1,748 in combined federal and Idaho tax. That money is not gone — it is yours, moved into a retirement account instead of a tax payment.

Push it to $10,000 and the saving rises to $3,495. At the 2026 contribution limit of $23,500, it reaches $7,713.

An HSA works the same way and is stronger still, because contributions avoid Social Security and Medicare as well as income tax. Both reduce your Idaho taxable income too, which is why the saving above is larger than the federal figure alone.

Who pays Idaho income tax

Residents of Idaho pay on all their income, wherever it was earned. Non-residents pay only on income sourced to Idaho — work physically performed there, property located there, business conducted there.

Part-year residents split the year, and the apportionment rules are genuinely fiddly. If you moved during 2026, this calculator will overstate or understate your Idaho bill depending on when you moved — it assumes a full year of residency.

Remote work has made this messier. Some states tax income based on where your employer is rather than where you sit, and a handful still apply a "convenience of the employer" rule. If you work across a state line, that question is worth answering before April.

Retirement income in Idaho

Idaho does not tax Social Security. It is one of 42 states plus the District that exempt benefits entirely — only eight still reach them in 2026.

What matters in Idaho is not how much retirement income you have but where it came from.

Idaho’s deduction is by source and by age together: you must be 65, or 62 and disabled, AND the income must come from a qualifying system — the Firefighters Retirement Fund administered by PERSI, an Idaho city police retirement fund outside Social Security, or the federal Civil Service Retirement System. A general private pension or 401(k) does not qualify. An un-remarried widow or widower can claim it even if the deceased spouse was not yet eligible.

We have not yet confirmed how Idaho treats military retirement pay. Thirty-seven states exempt it, so the odds are it is exempt here too, but we would rather say we have not checked than guess on your behalf.

The calculator above does not apply any of this — it models salary income with the standard deduction. If a meaningful share of your income is retirement income, treat that figure as an upper bound.

What this Idaho calculator leaves out

Being specific about the gaps is more useful than claiming there are none. This figure covers federal income tax, Social Security and Medicare, and Idaho state income tax on salary income, using the standard deduction.

itemised deductions beyond the standard one, credits such as the Child Tax Credit and the Earned Income Tax Credit, capital gains, dividends and other investment income, self-employment income and the tax that comes with it, the Alternative Minimum Tax — none of these are in the number above.

If your situation includes any of them, the result here is a starting point, not an answer. That is also why we publish which state figures we have checked against Idaho Department of Revenue and which we have not.

What has changed, and what changes next, in Idaho

We have not yet loaded a rate history for Idaho. Twenty-six states have cut income tax rates since 2021 and seven have moved from brackets to a single rate, so the direction of travel nationally is downward.

Where Idaho sits against similar states

On $85,000, the states closest to Idaho are California ($3,660), Georgia ($3,643), Maryland ($3,672). If you are weighing a move between any of these, state income tax is not the deciding factor — the gap is smaller than a single pay rise.

The nearest states that charge less are Georgia ($3,643), Montana ($3,442), Michigan ($3,362) — a saving of up to $290 a year at this salary.

Just above sit California ($3,660), Maryland ($3,672), Kansas ($3,943). And Oregon takes $6,604, $2,952 more than Idaho on the same salary.

What five different salaries actually cost in Idaho

The single most useful thing to see is how the total moves with income, because it does not move in a straight line. Here is the same calculation at five salaries, single filer, standard deduction:

$45,000 → $8,194 in tax (18.21%), leaving $36,806. $65,000 → $13,184 in tax (20.28%), leaving $51,816. $85,000 → $20,024 in tax (23.56%), leaving $64,976. $120,000 → $32,257 in tax (26.88%), leaving $87,743. $185,000 → $56,207 in tax (30.38%), leaving $128,793.

Between $45,000 and $185,000 the total rate rises by 12.2 points — from 18.21% to 30.38%. That is a smaller jump than most people expect from a salary that has more than quadrupled, and the reason is structural: federal brackets are marginal, so a raise never re-taxes what you already earned, and Social Security stops entirely above $184,500.

Look at the FICA line specifically. At $45,000 it is $3,443, which is 7.65% of gross — more than the $3,220 of federal income tax at that level. At $185,000 it is $14,122, or 7.63%. FICA is the tax that weighs most on modest incomes and least on large ones, and it is the one nobody talks about.

Your marginal rate is not what you pay

On $85,000 in Idaho the federal marginal rate is 22.00% — that is what the next dollar costs. What the whole salary actually cost in federal income tax is 11.61%, or $9,870. The gap between those two numbers is the single most misunderstood thing in US tax.

The reason is that brackets are marginal, not cliffs. Only the slice of income inside a bracket is taxed at that bracket's rate. The first $16,100 is not taxed at all, the next slice at 10.00%, and so on up. A pay rise that "pushes you into a higher bracket" never reduces your take-home — that fear is the practical cost of the confusion.

Idaho sidesteps the whole question with a single flat rate of 5.30%, so its marginal and effective rates are the same — almost. It still allows a $16,100 deduction, which pulls the effective rate slightly below the headline one, to 4.30%.

And there is a third rate that matters more than either: 23.56%, which is everything — federal, FICA, Idaho — as a share of gross. That is what actually left your pay. Never compare it against a marginal rate; they measure different things and the comparison suggests an error that is not there.

What a single flat rate does that brackets do not

Idaho charges a single rate of 5.30% rather than running brackets. Fifteen states now do this, and seven of them moved to it since 2021 — it is the clearest trend in US state tax policy of the past five years.

The practical difference is predictability. Your marginal and effective state rates are the same number once the $16,100 deduction is accounted for, so a raise costs exactly what the rate says and there is no bracket to worry about crossing. On $85,000 the state bill is $3,652.

The distributional consequence is the argument against it. A flat rate takes the same proportion from a $45,000 salary as from a $400,000 one, which means it is a heavier burden relative to what a modest household can absorb — though the $16,100 deduction softens exactly that end of the scale, and it is why the deduction matters more in a flat state than in a graduated one.

Watch for the exempt band specifically, because compiled sources miss it constantly. Ohio and Mississippi both charge what looks like a flat rate but tax nothing below a threshold — we found sources overstating Ohio's bill by 43% for exactly that reason. A "flat" state is not always flat from the first dollar.

What your next $10,000 is actually worth here

Going from $85,000 to $95,000 in Idaho raises your tax by $3,495, so you keep $6,505 of the $10,000 — an effective rate on the raise of 34.95%. That is the number worth having in a salary negotiation, and it is not the same as either your bracket or your average rate.

Notice that it is higher than your overall effective rate of 23.56%. New income is always taxed at the top, so the marginal cost of a raise exceeds the average cost of everything you already earn. That is the whole point of a progressive system, and it is also why a bonus feels more heavily taxed than a salary — it is stacked on top.

Bonuses have a wrinkle of their own. Employers often withhold them at a flat supplemental rate rather than at your actual marginal rate, which can take more or less than you owe. It comes out right at filing either way, but it explains why a bonus payslip so often looks wrong.

With no local income tax in Idaho, the cost of the raise is entirely federal, FICA and Idaho.

Five ways this calculation goes wrong

Adding FICA to the withholding. Boxes 4 and 6 of your W-2 are Social Security and Medicare. They are not advance payments of income tax and never come back as a refund. Only box 2 (federal) and box 17 (state) belong in a refund calculation, and including the others overstates it by thousands.

Comparing the effective rate against the marginal rate. Here that would mean setting 23.56% against 22.00% and concluding something has gone wrong. Nothing has: the first includes payroll and state tax, the second is federal income tax on the next dollar. They measure different things.

Assuming a flat state is flat from the first dollar. Ohio taxes nothing below $27,350 of taxable income and Mississippi nothing below $10,000, yet both are widely published as simple flat rates. That single omission overstated Ohio's bill by 43% in the sources we checked.

Assuming your city takes a cut. Idaho does not levy an income tax, and only fifteen states permit any city to. Budgeting for one that does not exist is the mirror of the previous mistake.

Using last year's figures. Bracket thresholds, the standard deduction and several state rates are indexed and move every January. Worse, states backdate: Georgia cut its rate in May 2026 with effect from 1 January, so a table published in April was correct when written and wrong by summer. That is why every figure on this site carries the date it was checked.

Deadlines and what you actually have to file in Idaho

Federal returns for 2026 are due on 15 April 2027. An extension gives you until 15 October to FILE, but not to PAY — anything owed still accrues interest from April, which is the part people misread. If you expect to owe more than $1,000 beyond withholding, the IRS expects quarterly estimated payments rather than a single settlement.

Idaho generally follows the federal calendar, and most states accept the federal extension automatically rather than requiring their own form. Check before assuming: a handful require a separate request, and the penalty for getting it wrong is charged on a bill you may not know you have.

With no local income tax there is no third return to worry about, which is worth something on its own: in states like Ohio and Pennsylvania a working household can face three separate filings a year.

Whatever your situation, the figures on this page are for planning. They assume a salaried filer taking the standard deduction, and they do not model itemised deductions, self-employment income, capital gains, or credits such as the EITC that can change the answer substantially.

Where the Idaho figures come from

Federal brackets and the standard deduction come from the IRS Revenue Procedure for 2026, read off the document itself rather than a summary of it.

The Idaho figures have been checked against Idaho Department of Revenue. Where our original data was wrong, the page says so rather than quietly fixing it — because a calculator that has never admitted an error is either new or not looking.

Every figure carries the date we last verified it, and the full log is published rather than kept internally.

Idaho income tax questions

Does Idaho have a state income tax?

Yes. Idaho taxes income at a flat 5.30%, the same rate at every income level.

How much is $85,000 after tax in Idaho?

A single filer earning $85,000 in Idaho keeps $64,976 for 2026. That is after $9,870 in federal income tax, $6,503 in Social Security and Medicare, and $3,652 in Idaho state tax — an effective rate of 23.56% across everything.

What is the top Idaho tax rate?

Idaho has a single rate of 5.30%, so there is no separate top rate.

Why is my Idaho tax bill different from this estimate?

This estimate uses the standard deduction and no credits beyond it. Real returns often include state-specific credits, itemised deductions, retirement income exclusions. It is built for planning, not for filing.

How much do I take home per paycheck on $85,000 in Idaho?

Paid every two weeks, $2,499 after federal tax, FICA and Idaho tax, from a gross of $3,269. Paid monthly, $5,415.

Does contributing to a 401(k) reduce my Idaho tax?

Yes. Traditional 401(k) contributions come out before both federal and Idaho income tax. On $85,000, contributing $10,000 cuts your combined bill by $3,495.

Is it cheaper to file jointly in Idaho?

On $85,000, filing jointly costs $15,141 against $20,024 filing single — $4,883 less. Whether that holds for you depends on both incomes, not just one.