Nice idea, Alan. Gig platform workers are exactly the group who get caught out at Self Assessment time, so a free, ad-free tool for that audience fills a real gap. A few points worth checking against what the calculator currently does, since these are the areas where most simple calculators go wrong.
Things the maths needs to handle - Other income. Most Uber, Etsy and Deliveroo earners also have a PAYE job. The side hustle profit sits on top of that salary, so it can land in the 40% band even if the hustle itself is small. A field for employed income is essential or the result will be badly understated.
- Scottish rates. Scotland has six income tax bands with different rates and thresholds. National Insurance stays UK-wide, but income tax does not. A simple England/Wales/NI vs Scotland toggle would sort it.
- Class 2 and Class 4 NICs. Class 2 is now treated as paid for profits above the small profits threshold (£6,725), and Class 4 is 6% between £12,570 and £50,270 then 2% above. Make sure those figures match the current tax year and are dated on the page.
- Trading allowance. The £1,000 allowance can be claimed instead of expenses, not alongside them. Many small Etsy sellers are better off with the allowance; a delivery rider with high mileage is usually better off claiming actual costs. Showing both options side by side would be genuinely useful.
- Payments on account. Once the bill goes over £1,000, HMRC asks for 50% of next year's estimate up front. First-year sellers get a nasty shock here, so flagging the cash flow impact would add real value.
- Student loans. Plan 1, 2, 4, 5 and postgraduate repayments all come through Self Assessment on self employed profits.
On the platform fee side, treating the platform's cut as an allowable expense is correct, but mileage (45p a mile for the first 10,000) is often the bigger deduction for drivers and riders, so a mileage input would be worth adding.
One last thought: platforms now report seller data to HMRC under the digital platform reporting rules, so a short note on the page explaining that HMRC already sees these figures would nudge users towards registering rather than ignoring it. Good luck with it.
