Tennessee Child Support Guidelines Calculator

An open-source, web-based presumptive child-support calculator implementing the Tennessee Child Support Guidelines (Tenn. Comp. R. & Regs. ch. 1240-02-04) and a companion Mississippi statutory-percentage worksheet (Miss. Code Ann. § 43-19-101).

Live calculator: https://csg.tcblaw.org

Built and maintained by The Carter Bowman Firm, PLLC. Free to use, including downloadable PDF worksheets. No login, no gate.

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What it does

• Computes the Basic Child Support Obligation (BCSO) from the 2022 DHS schedule, including the above-cap formula for combined AGI > $28,250/mo.
• Applies the Parenting-Time (PT) adjustment for standard and 50/50 arrangements, including the cross-credit method for equal parenting.
• Adds health insurance, work-related child care, recurring medical, and private school as additional expenses with the correct pro-rata split.
• Flags the statutory maximum PCSO by number of children (1240-02-04-.07(2)(c)) and surfaces deviation language when exceeded.
• Generates a printable PDF worksheet matching the structure of the official TN CS-101 / CS-102.

Every line of math cites the controlling regulation in src/lib/calc/citations.ts.

Disclaimer

This is an informational tool, not legal advice. The output is a presumptive estimate; actual orders depend on findings of fact, deviations, and trial-court discretion. Use of this calculator does not create an attorney-client relationship.

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Tech stack

• TanStack Start (React 19 + Vite 7) on Cloudflare Workers
• TypeScript (strict), Tailwind CSS v4, shadcn/ui
• Vitest for the calculation engine
• Supabase (managed via Lovable Cloud) for optional opt-in features

Run locally

bun install
bun run dev          # http://localhost:8080
bunx vitest run      # run the calculation test suite

The calculator engine in src/lib/calc/ runs entirely in the browser; no backend is required to compute or print a worksheet.

Deploy

The project deploys to Cloudflare Workers via the TanStack Start Vite plugin:

bun run build

To self-host, point any static/edge host that supports @cloudflare/vite-plugin output at the build artifact, or fork and deploy via Lovable / Cloudflare / your platform of choice.

Repository layout

src/lib/calc/             Pure calculation engine (TN)
  bcso.ts                 2022 DHS schedule + above-cap formula
  calc.ts                 PT adjustment, cross-credit, add-ons, PCSO cap
  citations.ts            Rule citations for every line of math
  __tests__/              Vitest fixtures (Stories 1–5 + edge cases)
src/lib/calc/ms/          Mississippi statutory-percentage worksheet
src/components/calculator/ React UI + PDF rendering
src/routes/                File-based routes (TanStack Router)

Rule-citation framework

Every computed value carries a citation to its controlling rule (src/lib/calc/citations.ts). When the guidelines change, edit the citation constant and the BCSO table in src/lib/calc/data/ — the UI and PDF inherit the update automatically. The test suite locks the math at named scenarios (see __tests__/calc.test.ts and __tests__/stories.test.ts).

Contributing

See CONTRIBUTING.md. Bug reports for the math are especially welcome — please include the exact inputs and the expected vs. actual result.

License

MIT. Includes a non-legal-advice disclaimer.