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 = "0.1.2"

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