About a month ago I started building QuarterPerfect — a bookkeeping tool aimed at UK sole traders and landlords, specifically designed around the MTD ITSA changes coming into effect this year (first quarterly deadline: 7 August).

A bit of background on me firstly.

I'm not a senior developer. My previous project was a small roster app that converted an XLSX shift rota into a calendar with annual leave support — mostly built for me and a few colleagues at work. Nothing with real users, nothing with payments or compliance requirements. QuarterPerfect is a significant step up from that.

QuarterPerfect offers users bank statement import (CSV and PDF), transaction categorization with receipt matching, merchant rules for auto-categorizing recurring transactions, and a read-only accountant share link so clients can hand off clean records without chasing. It's web-first with a mobile app in testing.

The technical side was challenging but learnable. The harder thing was building in a domain I have no real background in. The HMRC/MTD space has a lot of nuance, treatment of different income types, what "quarterly updates" actually mean vs the annual return, what accountants need vs what HMRC needs. Getting that wrong isn't a UX problem, it's a liability problem.

The second hard thing was learning to work effectively with AI assistance. I used Claude and Perplexity heavily throughout. Early on I'd accept output too uncritically and build on shaky foundations. The shift that helped most was treating it less like a code generator and more like a pair programmer, the decisions still have to be mine, and I have to understand what I'm shipping well enough to defend it. Honestly though, one really good work flow was to give Perplexity my ideas and have it generate detailed prompts for Claude, I would then post results back to Perplexity. A LOT of copy and pasting but results were spot on. I also had them both agree on a project management structure, which REALLY helped keep things tidy.

It's still in testing, with no public users yet. The product works end-to-end but I'm not comfortable pushing it to strangers until I'm more confident in the compliance side. Also I want the app to be native to iOS and Google Play store, the latter requires me to have a minimum of 12 testers using the app in some capacity for 14 days, I haven't reached the minimum amount yet, even after asking for help from friends on social media, quite deflating to be honest!

Has anyone else built in a regulated or compliance-heavy space without vast expertise? How did you handle the gap between "this works" and "this is correct enough to trust with someone's tax records" for example.

Has anyone else found the AI-assisted development workflow genuinely helped them create a working/useful website/app, what has been your experience?

I'm not looking to recruit users from this post, the product requires signup to evaluate properly anyway. More curious whether anyone's been in a similar position and what they did to get it over the line.

Thanks,

James