HustleTax
- Client project
HustleTax is a free UK tax calculator for people with a side hustle, freelancers and the self-employed. It shows the income tax, National Insurance and student loan repayment due on side income for the 2025/26 or 2024/25 tax year, and how much you keep.
Technologies
- Python
- Flask
- JavaScript
- HTML/CSS
The Challenge
Freelancers and side hustlers in the UK often don't know how much tax they owe until it's too late. Existing HMRC tools are complex and intimidating, leading many to either overpay or face unexpected tax bills.
The Solution
A simple calculator that works out the tax on side income as you type, with no sign-up. It stacks side profit on top of your salary, picks the £1,000 trading allowance or actual expenses, whichever saves more, and adds Class 4 National Insurance and student loan repayments. Class 2 NI is not charged, as it stopped being compulsory from 2024/25. The result is a take-home figure with a full breakdown.
UX & Design
The calculator is on the first screen, with the inputs on one side and the breakdown on the other, and it updates as you type, with no submit button. Money fields open a numeric keypad on mobile and add thousands separators. Explainer cards, tax tips and an FAQ built from native expandable sections sit below. On small screens the menu folds into a burger button, and Escape closes the menu and the share dialog.
Development
The whole calculation runs in the browser in plain JavaScript, with HMRC rates for both tax years kept in the page script, so a result needs no server call. It handles the Personal Allowance taper above £100,000, Blind Person's Allowance and five student loan plans. Inputs are saved in local storage and can be shared as a link with URL parameters. The page carries WebApplication and FAQPage structured data.
Key Features
- Instant estimate for the 2025/26 and 2024/25 tax years
- Automatic choice between the £1,000 trading allowance and actual expenses
- Income tax worked out on top of employment income
- Class 4 National Insurance on side hustle profit
- Student loan repayments for Plans 1, 2, 4 and 5 and the Postgraduate Loan
- Share on X or WhatsApp, copy a link or print the breakdown
- Tax tips and an FAQ on Self Assessment, expenses and deadlines
Gallery
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