uk-tax

A Rust library that calculates UK PAYE Income Tax and Class 1 National Insurance contributions with historical tax year support.

Supports historical tax years (2011/12 to 2025/26) and allows custom personal allowances to be specified, if needed.

Features

Calculate annual Income Tax (income_tax)
Calculate annual Class 1 employee NI (national_insurance)
Tax year constants from 2011/12 to 2025/26
Flexible personal allowance support
MIT licenced

Installation

Add this to your Cargo.toml:

[dependencies]
uk-tax = "0.1.3"

Usage

use uk_tax::{income_tax, national_insurance, TAX_YEAR_2025};

fn main() {
    let gross_income = 60_000.0;

    // Calculate income tax
    let tax = income_tax(gross_income, &TAX_YEAR_2025, None).unwrap();
    println!("Income Tax: £{:.2}", tax);

    // Calculate National Insurance
    let ni = national_insurance(gross_income, &TAX_YEAR_2025, None);
    println!("NI: £{:.2}", ni);
}

Future developments

Planned or potential improvements:

Automatic personal allowance tapering above £100,000 per annum
Default to the current tax year automatically
Add support for Scottish and Welsh income tax bands
Add other NI classes (e.g., Class 2, Class 4)

Licence

MIT Licence.
See LICENSE for details.

Contributing

Pull requests and issues are welcome!

Author

Written by Laurence Stock-Tully

uk-tax 0.1.3