Colorado vs Idaho: state income tax, 2025
For reference household P1 (single, $60,000 of wages), Colorado charges $1,947or less and Idaho charges $2,100or less. Both are bounded in the same direction, so the difference between them cannot be stated.
Both figures are a hypothetical full-year resident return for tax year 2025, over the same federal return, and count state income tax only. Neither is a relocation estimate: moving mid-year means two part-year returns, which this site does not figure. “Or less” means a mechanism the engine does not yet model would lower the figure; “or more” that it would raise it.
Six households, both states
| Household | Colorado | Idaho | Colorado minus Idaho |
|---|---|---|---|
| P1 Single, $60,000 of wages | $1,947or less | $2,100or less | not bounded |
| P2 Married filing jointly, $150,000, two children | $5,214or less | $5,371or less | not bounded |
| P3 Single, $85,000 wages + $15,000 long-term gain + $3,000 qualified dividends | $3,839or less | $4,379or less | not bounded |
| P4 Married retirees, $40,000 Social Security + $30,000 pension + $20,000 IRA, both 65+ | $0or less | $10or less | not bounded |
| P5 Head of household, $45,000, one child | $941or less | $428or less | not bounded |
| P6 Single, $1,200,000 of wages + $500,000 long-term gain | $74,272or less | $89,020or less | not bounded |
Full-year resident figures for 2025, state income tax only, with the same federal return in every column. Every figure is provisional. “Not shown” and “not figured” mean the engine will not state a number it cannot stand behind; hover for why.
Where the difference comes from
Colorado
- Where the return starts. Starts from federal taxable income, after the federal deduction.
- Rate. A flat 4.4% on taxable income.C.R.S. §39-22-104; Colorado Book 104 (2025 Individual Income Tax Filing Guide): "The income tax rate is currently 4.4%." The published tax table is headed "2025 Colorado Income Tax Table with tax rate of 4.4%". (checked 2026-08-05)
- Added to income. Municipal bond interest from other states.C.R.S. §39-22-104(3)(b): added is the interest excluded federally under IRC §103(a) "on obligations of any state or any political subdivision thereof, other than interest income on obligations of the state of Colorado or any political subdivision thereof which are issued on or after May 1, 1980"; Book 104, DR 0104 line 9 Other Additions: "Bond interest: Interest earned from bonds issued by any state or political subdivision, but not bonds issued by the State of Colorado or its political subdivisions on or after May 1, 1980." (checked 2026-10-20)
- Excluded from income. Social Security benefits.DR 0104AD lines 3 and 5 — 65 or older on 31 December 2025: the entire federally taxable amount. At least 55 but not yet 65: the entire amount where federal AGI does not exceed $75,000 (single) or $95,000 (married filing jointly), otherwise limited to $20,000. (checked 2026-08-05)
- Excluded from income. Retirement income.DR 0104AD lines 4 and 6 — 65 or older: $24,000 minus the amount on line 3, or the total taxable pension/annuity income, whichever is smaller. At least 55 but not yet 65: $20,000 on the same terms. Per person, never intermingled between spouses. (checked 2026-08-05)
- Earned income credit. 50% of the federal credit, refundable.
Idaho
- Where the return starts. Starts from federal adjusted gross income.
- Rate. 2 brackets for a single filer, from 0% to 5.3%; the top rate starts at $4,811 of taxable income.Idaho Code §63-3024; 2025 Individual Income Tax Instructions (EIN00046), "What’s New for 2025": "Effective January 1, 2025, the individual income tax rate is 5.3%." The Form 40 line 20 worksheet subtracts $4,811 (single or married filing separately) or $9,622 (married filing jointly, head of household, or qualifying surviving spouse) before applying the rate. (checked 2026-08-05)
- Standard deduction. $15,750 single, $31,500 married filing jointly.Idaho Code §63-3022(j); 2025 EIN00046 Standard Deduction Worksheet: $15,750 single or married filing separately, $31,500 married filing jointly or qualifying surviving spouse, $23,625 head of household — the federal figures, which Idaho adopts. (checked 2026-08-05)
- Added to income. Municipal bond interest from other states.Idaho Code §63-3022M(1); 2025 EIN00046, Form 39R Part A line 3: "Enter the amount of interest and dividends, minus related expenses, that you received from municipal bonds of other state governments, their counties, and their cities … This isn’t income you report on your federal return." (checked 2026-10-20)
- Excluded from income. Social Security benefits.2025 EIN00046, Form 39R Part B line 7: "Deduct the portion of your Social Security benefits, benefits that the Railroad Retirement Board pays, or Canadian Social Security benefits … that’s taxable on your federal return." (checked 2026-08-05)
What this comparison leaves out
Mechanisms the engine does not model yet. Each one is named with the direction it would move the figure, which is where every “or less” above comes from.
Colorado
- Colorado earned income tax credit for ITIN filers and childless filers under 25 who have no federal EITC (DR 0104TN, DR 0104CR line 9) C.R.S. §39-22-123.5 — the figure is too high without it
- Colorado child tax credit and family affordability tax credit where a qualifying child is on a return at or under the AGI ceiling (DR 0104CN) C.R.S. §39-22-129 — the figure is too high without it
- U.S. government interest subtraction (DR 0104AD line 2) C.R.S. §39-22-104(4)(a) — the figure is too high without it
- Qualifying charitable contribution subtraction for non-itemizers whose gifts are not entered on the return (DR 0104AD line 12) C.R.S. §39-22-104(4)(m) — the figure is too high without it
- Social Security subtraction for a survivor under 55, and military retirement under 55 DR 0104AD lines 3/5 and 7/8 — the figure is too high without it
- Child and dependent care expenses credit and low-income child care credit (DR 0347) C.R.S. §§39-22-119, 39-22-119.5 — the figure is too high without it
- Colorado-issued (on or after 1 May 1980) and territory bond interest inside the DR 0104 line 9 addition, and the bond premium and related expenses it is reduced by C.R.S. §39-22-104(3)(b) — the figure is too high without it
- Credit for tax paid to another state C.R.S. §39-22-108 — the figure is too high without it
Idaho
- Retirement benefits deduction (Form 39R Part B line 8) Idaho Code §63-3022A — the figure is too high without it
- The other Form 39R Part B subtractions — U.S. government obligation interest, energy efficiency upgrades, alternative energy devices, technological equipment donations, the Idaho capital gains deduction, health insurance premiums, and the Idaho college and medical savings accounts Idaho Code §63-3022 — the figure is too high without it
- Idaho-issued municipal interest inside the Form 39R Part A line 3 addition Idaho Code §63-3022M — the figure is too high without it
- Permanent Building Fund tax exemptions the return does not record Idaho Code §63-3082 — the figure is too high without it
- Credit for income tax paid to other states (Form 39R Part D) Idaho Code §63-3029 — the figure is too high without it
Taxes that are not income tax. Property tax, sales and excise taxes, and state payroll levies such as disability or paid-leave contributions are not counted here, and none of them is small. Federal tax is excluded because it is the same in both columns. A state income tax comparison is not a total tax burden comparison; see methodology.
Data status
Colorado. 2025 rules are provisional; engine coverage is implemented, with 8 mechanisms declared as not yet modelled. See the 2025 rate table.
Idaho. 2025 rules are provisional; engine coverage is implemented, with 5 mechanisms declared as not yet modelled. See the 2025 rate table.
2026 state rules are not built yet, so this page compares 2025 only. Track status on the 2025 data status board.
Try it with your own return
The six households above are reference cases. Your own return will land differently. Compare Colorado and Idaho over your own return — it stays in your browser.