Sweetwater County operates under Wyoming's 9.5% residential assessment ratio system (WY Const. Art. 15) — taxable AV = 9.5% of fair market value. Sweetwater's consolidated mill levy is approximately 56.00 mills per $1,000 of AV, producing typical effective rates around 0.57% on full market value. Wyoming has the lowest effective property tax rates in the United States (~0.55% statewide median). HB 45 of 2024 caps year-over-year residential AV growth at 4% (applied automatically — no application required), among the more generous AV-cap mechanisms in the US. No state income tax.
How the bill is built
Wyoming's calculation is unusually transparent: Tax = Market Value × 9.5% × Mill Levy / 1000. A $400,000 Sweetwater home with 56 mill levy: AV = $38,000 → Tax = $$2,128. The 9.5% AR is constitutionally fixed (WY Const. Art. 15) — commercial is also 9.5%, industrial is 11.5%, minerals 100%. HB 45 of 2024's 4% AV growth cap applies automatically; no exemption form required. Bills issue annually; first half due November 10, second half due May 10 (Teton uses August 1 + July 1 schedule). 18% annual penalty for late payment.
2026 Sweetwater County rate breakdown (consolidated mill levy per $1,000 of AV (residential AV = 9.5% × FMV; HB 45 of 2024 caps year-over-year AV growth at 4%; among lowest US effective rates ~0.55%), Green River district)
| Taxing entity | Rate |
|---|---|
| Sweetwater County School District 1 | 30.0000 |
| Sweetwater County (general) | 9.5000 |
| City of Rock Springs | 8.5000 |
| Western Wyoming Community College | 8.0000 |
| Combined total | 56.0000 |
As of April 27, 2026 · From Sweetwater County Assessor.
Deductions and exemptions for 2026
Wyoming's primary structural benefit is the constitutional 9.5% residential assessment ratio (WY Const. Art. 15) — only 9.5% of your home's fair market value is taxed. On top of that, four additional mechanisms provide relief: the HB 45 of 2024 4% AV growth cap (automatic), the Long-Term Senior Exemption (50% off for 65+ with 25+ years WY residency), the Property Tax Refund Program (refundable cash for qualifying lower-income homeowners), and the Veterans Exemption ($3,000 AV reduction).
HB 45 of 2024: 4% Annual AV Growth Cap
Wyoming's most significant recent property tax relief — caps year-over-year residential AV increases at 4%, applied to both the residential structure and associated land. Effective tax year 2024+. Applies AUTOMATICALLY — no application required. Cap resets at sale or major physical improvement (additions, new construction). The cap was extended/refined by SB 71 of 2025. For Teton County and other fast-appreciating markets where home values rose 30%+ in single years from 2020-2023, this prevents the assessed value from spiking with the market.
Long-Term Senior Exemption (50% Reduction)
For homeowners 65+ who have paid Wyoming property taxes for at least 25 years on the same primary residence (or who have continuously owned it for 25+ years). Provides a 50% reduction in the residential AV. Apply with the County Assessor by March 1 of the tax year. Annual application required. Combined with the 4% AV cap and the underlying 9.5% AR, qualifying long-term Wyoming seniors pay extraordinarily low effective rates. Particularly valuable in Teton County where Long-Term Senior Exemption holders pay ~0.20-0.25% effective on multi-million-dollar homes.
Property Tax Refund Program
Refundable cash refund for qualifying lower-income Wyoming homeowners. Maximum refund equal to half of the median Wyoming residential property tax bill. Income limit: HHI ≤ 145% of county median household income (expanded by HB 45 of 2024 from 125%). Apply with the Wyoming Department of Revenue or your County Treasurer between January 1 and June 15 each year. Annual application required. Not income-tax-form based — it's a direct refund check.
Veterans Exemption
$3,000 AV reduction for honorably discharged war-era veterans (~$240/year value at typical 80-mill levy). Surviving unremarried spouses receive an $800 AV reduction. Apply with the County Assessor; one-time application unless residency changes. Wyoming does NOT have a categorical full-exemption for 100% disabled veterans like NJ, MD, VA, or other categorical-exemption states — the $3,000 AV reduction is the only state-level vet benefit. The substantial veteran population on F.E. Warren Air Force Base (Cheyenne) and Camp Guernsey (Platte County) widely uses this exemption.
Appealing your assessment
Assessment notices are mailed in early April (varies by county). Property owners have 30 days from the date of the Notice of Assessment to file a formal appeal with the County Assessor. The County Board of Equalization hears appeals through July; decisions may be appealed to the Wyoming State Board of Equalization within 30 days, then to Wyoming District Court. The burden of proof is on the homeowner — bring evidence of comparable sales, recent appraisals, or property condition issues. Most appeals are resolved at the County Assessor or Board of Equalization level. The 4% AV growth cap (HB 45 of 2024) limits the immediate appeal need for assessment shock since the cap absorbs much of the year-over-year volatility.