Methodology & sources

Machine-readable endpoints

Public URLs on this host (also listed at /data):

• /data/counties.json — millage, OIR averages, PA/tax collector links
• /data/amendment3.json — PCPAO summary and Walczak Tables 1–5 extracts
• /data/millage.csv — county millage mirror
• /llms.txt and /llms-full.txt — page map and sourced figures for AI agents
• /sitemap-index.xml

Primary sources

• Pinellas County Property Appraiser, Proposed 2026 Florida Property Tax Amendment 3 (CS/HJR 1F) FAQs — what Amendment 3 does, timing, homestead vs non-homestead, millage vs taxable value.
• Jared Walczak, Amendment 3 Could Shift Tax Burdens to Renters (Walczak Policy Consulting, September 2026) — statewide and county rental-tax shift under a revenue-neutral millage increase. Tables 1–5 extracted on 2026-10-18.
• Florida Division of Elections, Constitutional Initiatives — Increased Homestead Exemption; Lower Cap on Increases in Non-Homestead Property Assessments — ballot summary for CS/HJR 1F.
• Florida Revenue Estimating Conference, Homestead Exemption Increases; Assessment Increase Limitation 10% to 5% (July 10, 2026) — fiscal cost estimates cited by Walczak.
• Florida Department of Revenue Property Tax Data Portal
• Florida DOR, 2025 Maximum Millage Levy Calculation Compliance (MillCapComp25), dated 01-26-26 — county BCC millage. County BCC millage is the county-government operating rate, not the total property-tax rate. Cities, school boards, MSTUs, and special districts add more.
• Florida Office of Insurance Regulation, Property Insurance Stability Report (January 1, 2026) — county homeowners and condo-unit averages as of 2025-09-30.
• FEMA Flood Map Service Center
• Florida DBPR condominium inspections and SB 4-D FAQs
• Fla. Stat. § 193.155 (Save Our Homes), § 193.1554 (non-homestead residential 10% cap), and § 193.1555.
• Lee County Property Appraiser, 10% Assessment Limitation FAQ — purchase does not carry the prior owner’s cap.

Millage files used for each county

CSV mirror: data/millage.csv (copied to the built site as /data/millage.csv).

Calculator formulas

Implemented in src/lib/calc.ts and unit-tested in src/lib/calc.test.ts.

• Annual property tax = round_cents(purchase_price × millage / 1,000).
• Monthly P&I = standard amortizing payment on (price − down payment). Rate input is a percent (6.5 means 6.5%). Zero rate splits principal evenly.
• Monthly cash flow = rent − (P&I + tax/12 + insurance/12 + HOA + flood/12 if flood zone is yes).
• NOI = rent×12 − annual tax − insurance − HOA×12 − flood (if yes). Cap rate = NOI / purchase price.
• Cash-on-cash = (monthly cash flow × 12) / down payment. Undefined at zero down.
• Rounding is half-up to the cent.

What we found vs what we could not find

Found

• Walczak Table 4 for all nine counties on this site, and Table 5 for Tampa, St. Petersburg, Orlando, Winter Park, Lakeland, Bartow, St. Cloud, Oviedo, Sanford, and Palm Bay.
• Tax year 2025 county BCC millage from DOR MillCapComp25, plus an official example total millage from each county’s PA or tax collector millage sheet.
• School millage components from those county sheets.
• OIR county average homeowners and condo-unit premiums including wind, as of September 30, 2025.
• PCPAO’s legal description of Amendment 3, 2026 homestead $51,411, Pinellas non-school average mills 12.2011, and estimated homestead savings illustrations for Pinellas only.

Not found — and therefore not invented

• Walczak Table 5 cities for Lake County and Volusia County. County pages say so.
• A published citywide millage total for St. Petersburg, Winter Park, and Palm Bay in the county sheets we extracted. Those city pages say so and fall back to the county example millage in the calculator.
• A single official “unincorporated countywide” millage for Brevard. The tax collector sheet is by millage code; totals on that sheet range from 10.0769 to 18.1121. The calculator default is the first published total (12.3894), labeled as such.
• A Florida OIR county average for landlord / DP-3 dwelling policies. Homeowners averages are used only as a labeled placeholder.
• A FEMA county-average flood premium we could assign to every I-4 rental. Flood is parcel-level; the calculator requires a user-entered flood premium when flood zone is yes.
• An official average condo special-assessment dollar amount. We describe the SB 4-D / SIRS / milestone rules and stop.
• 2026 final millage (TRIM season was still ahead of some 2026 certifications when this page was built). We publish 2025 adopted millage and date it.
• Non-ad valorem assessments (garbage, fire fees, lighting). They are not millage and are omitted from tax estimates.

What this site will not do

No lender or title-company referral links. The owner’s Florida real estate license is in progress; RESPA risk is why those categories are excluded even as placeholders. Affiliate mentions of Stessa or Baselane are future bookkeeping/banking tools, not loan origination.