CT Mill Rates Connecticut
Connecticut Property Tax Estimator

Know the cost
before you build.

Enter your town and project details to instantly estimate your property tax impact — using real mill rates for all 169 Connecticut towns.

All 169 CT towns FY 2024–2025 mill rates Free · No signup Architects & homeowners
KNOW YOUR Build
Step 1 — What are you building?
Step 2 — Location & project details
Addition · Colchester, CT
New home value
Annual taxes (new)
Monthly increase
added to your bill
Current assessed value (70%)
Value added by project
New assessed value
Mill rate ()
Current est. annual taxes
New est. annual taxes
Annual tax increase

Mill rate source: CT Office of Policy and Management · FY 2024–2025 · Assessment ratio: 70% per CT state law

These estimates use Connecticut's 70% assessment ratio and official FY 2024–2025 mill rates. Actual taxes depend on your assessor's valuation of the completed project, applicable exemptions, and any special district overlays. Construction cost is estimated from regional CT averages if not entered manually. Always verify with your local town assessor before making financial decisions.

View all 169 CT town mill rates — sortable, searchable, with full source references
View mill rates table →
How Know Your Build estimates your taxes
The formula

Connecticut assesses all property at 70% of market value by state law. Know Your Build estimates the value your project adds, then applies your town's real mill rate from the CT Office of Policy and Management.

Assessed value = home value × 70%
Annual tax = (assessed ÷ 1,000) × mill rate

Mill rates are updated annually. The FY 2024–2025 rates are currently in effect for all 169 Connecticut municipalities.

Example — Hebron, CT
Current home value: $400,000
800 sq ft addition added
Est. value added: ~$136,000
New home value: $536,000
Assessed at 70%: $375,200
Hebron mill rate: 35.67
Current taxes: $9,828/yr
New taxes: $13,381/yr
Tax increase: ~$3,553/yr · $296/mo