# SCD Bond Calculator

A self-contained bond return calculator widget for [Stirchley Community Development (SCD)](https://www.stirchley.coop/) — a community housing co-operative in Stirchley, Birmingham, UK.

Potential investors can model returns on SCD community bonds across four interest models (compound/simple × at-maturity/paid-yearly), see a year-by-year breakdown, and understand the security tier and UK tax implications of their investment.

## Features

- **Three inputs** — investment amount (£20k–£10M), interest rate (0–3.5%), term (5–30 years)
- **Four payout methods** — compound at maturity, compound paid yearly, simple at maturity, simple paid yearly
- **Summary cards** — total repayment, total interest, per-year income, effective annual rate (CAGR)
- **Security tier** — unsecured (< £150k), tertiary charge (£150k–£500k), secondary charge (> £500k)
- **Tax estimates** — basic / higher / additional rate UK income tax (before Personal Savings Allowance)
- **Year-by-year table** — full breakdown with collapsible detail and totals row

## Usage

Open `calc.html` in any browser. No build step or server required — the widget is a single, self-contained HTML file that can be embedded directly as a WordPress Custom HTML block.

## Bond offer

Refer to the [SCD Bond Offer Document](https://www.stirchley.coop/wp-content/uploads/2026/05/SCD-Bond-Offer-2026-25-May-2026.pdf) for full terms, risks, and legal details.

## License

AGPL-3.0 — see [LICENSE](LICENSE).