Idaho Property Tax Calculator (Assessed Value & Millage Rates)

With a statewide average effective property tax rate of 0.43%, Idaho sits at #47 nationally, among the ten lowest effective property tax rates in the country. That's well under the national average of roughly 1.0%. Within the West, where the average effective rate runs near 0.71%, Idaho sits well below the regional norm too.

That revenue underwrites the basics (public schools, county government, emergency services) the same way it does across most of the West, though the specific mix of school, county, and municipal millage varies by jurisdiction within Idaho.

For anyone underwriting a purchase in Idaho, this effective rate is the starting point for modeling PITI escrow and cash-on-cash returns. The worked example below walks through the full calculation on a sample home price, so the math is transparent from assessed value to monthly payment.

Idaho's homeowner's exemption removes half the value of an owner-occupied home, up to a statutory maximum, before any levy applies. Combined with a circuit breaker that reduces bills for low-income seniors and disabled owners, it means the rate an Idaho owner actually pays diverges sharply from the posted levy rate.

None of that detail is asked for here. This calculator works one level up, applying Idaho's average effective property tax rate of 0.43% to the value you enter. That rate is the ratio of property taxes actually paid to home value across the state, so the assessment ratios, caps, and exemptions described above are already baked into it.

Working through it in order:

1. Start from market value. County assessors value property annually as of January 1.
2. Take off the homeowner's exemption. It covers 50% of the home and up to one acre of land, capped at the statutory dollar limit.
3. Multiply by the effective rate. At 0.43%, a $400,000 home in Idaho comes to $1,720 a year before any exemption you enter above.
4. Divide by twelve for escrow. That same home works out to $143.33 a month set aside in a mortgage escrow account.
5. Compare it against your own bill. Because the exemption is capped in dollars, its proportional benefit shrinks as home values rise. Your county's number is the one that governs; this figure tells you whether it is roughly where an Idaho home of that value ought to land.

Using this calculator's baseline inputs: a $400,000 home in Idaho, taxed at the state's 0.43% average effective rate (rank #47 of 50 states).

1. Start with the assessed value. The home is assessed at its full $400,000.00 market value, with no homestead exemption applied in this baseline scenario.
2. Apply the effective rate. $400,000.00 × 0.43% = $1,720.00 in annual property tax, Idaho's statewide average effective rate.
3. Convert to a monthly escrow. Lenders typically collect property tax in twelve equal installments alongside principal and interest: $1,720.00 ÷ 12 = $143.33 per month.
4. Project a five-year hold. At a flat rate, five years of ownership totals $1,720.00 × 5 = $8,600.00, before any reassessment, exemption change, or millage increase.

At 0.43%, Idaho carries one of the lightest property tax burdens in the country, ranking #47 of 50 states, though actual bills still vary by county and municipality.

Idaho's 0.43% effective rate ranks 47th of 50. The twelve rows above apply that one rate to twelve values, so the schedule is linear and there is no threshold anywhere in the Idaho path to walk across. The engine computes market value minus your exemption entry, times 0.0043, divided by twelve for the escrow figure.

Two rungs. Row 3 values the property at $200,000 and returns $860.00 a year, $71.67 a month. Row 6, the $400,000 baseline, returns $1,720.00 and $143.33. The doubling is exact, which is what a flat effective rate guarantees and what makes the marginal figure below usable at any value on the sweep.

The marginal figure. Each additional $10,000 of Idaho market value costs $43.00 a year, $3.58 a month. The engine returns $1,763.00 at $410,000 against $1,720.00 at $400,000. A $100,000 increase in a county's valuation therefore costs $430.00 a year.

The reverse question. A $2,500 annual budget carries $581,395.35 of Idaho market value, where the engine returns exactly $2,500.00 and $208.33 a month. Anyone weighing a move up the Boise market can read the ceiling directly off that figure rather than iterating on price.

The homeowner's exemption, which this engine flattens. Idaho exempts 50% of a primary residence's value up to a statutory dollar cap, $125,000 in recent years. Entering $125,000 takes taxable value to $275,000 and the annual bill to $1,182.50, a $537.50 saving. That is the right answer for a $400,000 home, because 50% of $400,000 is $200,000 and the cap binds first. It stops being right below $250,000 of value, where the 50% rule binds instead of the cap and the exemption should be half the value rather than the full $125,000. The engine has no percentage-of-value logic at all; it subtracts whatever dollar figure you enter, so on a lower-value Idaho home you must work the 50% out yourself before entering it.

The base error, priced. Idaho counties assess at full market value, so the 0.43% belongs on the purchase price and not on some fraction of it. Applying it to a 70% figure out of habit carried over from another state returns $1,204.00 on the baseline instead of $1,720.00, understating by $516.00 a year. The circuit breaker property tax reduction for low-income seniors and the separate 3% annual budget growth limit on Idaho taxing districts are both absent from this calculation.

• Specific hyper-local county and municipal millage district variations within Idaho.
• Local Improvement District (LID) assessments. Idaho cities can form LIDs under state law to bill an additional assessment to benefiting parcels for sewer, water, sidewalk, or street improvements, layered on top of the base county and school millage.
• Commercial vs residential assessment classification differentials.
• Property tax appeal reductions or localized board of equalization adjustments.

• Confusing Market Fair Value with Assessed Basis: Some jurisdictions assess property at fractional ratios rather than 100% of market value.
• Failing to File Homestead Paperwork: Homestead exemptions are rarely automatic; homeowners must file timely paperwork with the county appraisal district.
• Underestimating Post-Sale Supplemental Assessments: Purchasing a newly constructed or reassessed property often triggers catch-up supplemental tax bills.
• Ignoring Property Tax Appeal Windows: Missing the annual 30-to-60 day statutory protest window forfeits the right to challenge over-assessed property values for that tax year.

• U.S. Census Bureau: American Community Survey (ACS) Real Estate Assessment Benchmark Data. census.gov/programs-surveys/acs
• Idaho State Tax Commission: Property Tax Assessment Guidance. tax.idaho.gov