taxc

UK Tax Calculator for Capital Gains and Income.

Calculates UK taxes from JSON transaction input, implementing HMRC share identification rules for CGT (same-day, bed & breakfast, section 104 pool).

Installation

cargo install --git https://github.com/ascjones/taxc

Commands

All commands accept an optional positional FILE (JSON). If omitted or set to -, input is read from stdin.

taxc summary transactions.json -y 2025
taxc report transactions.json
taxc pools transactions.json --daily
taxc schema input

taxc summary - Tax Calculations

Aggregated CGT and income calculations. Use -y 2025 for a tax year, or --from/--to for a date range. Add --json for machine-readable output, -t higher for different tax bands.

taxc report - Tax Report

Self-contained HTML report opened in your browser, with summary cards, interactive filtering, expandable disposal matching details, and color-coded tags/rules. Use -o file.html to save instead, or --json for structured data.

taxc pools - Pool Balances

Section 104 pool balances over time. Year-end snapshots by default, or --daily for daily history.

taxc schema - Format Reference

Print JSON schemas for input (taxc schema input, default) or output (taxc schema output) formats. Schemas are also checked into schema/ for version tracking.

All filtering commands share: -y/--from/--to (date), -a (asset), --event-kind (disposal/acquisition), --exclude-unlinked.

Input Format

JSON with top-level assets and transactions fields. Run taxc schema input for the full schema.

Three transaction types: Trade (asset swap via sold/bought), Deposit (asset received), Withdrawal (asset sent). Transactions can be tagged for tax classification (income types, gifts, transfers, no gain/no loss).

Example

{
  "assets": [
    { "symbol": "BTC" },
    { "symbol": "ETH" },
    { "symbol": "AAPL", "asset_class": "Stock" }
  ],
  "transactions": [
    {
      "id": "tx-001",
      "datetime": "2024-01-02T09:00:00+00:00",
      "account": "kraken",
      "type": "Trade",
      "sold": { "asset": "GBP", "quantity": 1000 },
      "bought": { "asset": "BTC", "quantity": 0.025 }
    },
    {
      "id": "tx-002",
      "datetime": "2024-08-31T10:00:00+00:00",
      "account": "kraken",
      "type": "Trade",
      "sold": { "asset": "BTC", "quantity": 0.01 },
      "bought": { "asset": "ETH", "quantity": 0.5 },
      "valuation": { "base": "ETH", "rate": 2000, "quote": "USD", "fx_rate": 0.79 }
    },
    {
      "id": "tx-003",
      "datetime": "2024-10-01T00:00:00+00:00",
      "account": "ledger",
      "type": "Deposit",
      "tag": "StakingReward",
      "amount": { "asset": "ETH", "quantity": 0.01 },
      "valuation": 20
    }
  ]
}

HMRC Share Identification Rules

CGT calculations implement the HMRC share matching rules in order:

1. Same-Day Rule - Match disposals with acquisitions on the same day
2. Bed & Breakfast Rule - Match with acquisitions within 30 days after disposal
3. Section 104 Pool - Match remaining shares from the pooled cost basis

Tax Years Supported

• CGT annual exempt amounts and rates for 2024/25 onwards
• Income tax rates for basic, higher, and additional rate taxpayers

Development

Enable pre-commit hooks (runs fmt, clippy, and tests):

git config core.hooksPath .githooks

Project Structure

• src/main.rs - CLI entry point
• src/cmd/ - CLI command implementations
• src/core/ - Domain logic and tax calculations (flat public surface via re-exports)

License

MIT