FallAccount Elite
Live: sjgant80-hub.github.io/fallaccount
Sovereign accounting for UK sole traders. 8+1 AI swarm. Single HTML file. Zero SaaS. Your data stays in your browser.
The tax maths is proven — not just typed
The money a sole trader cannot afford to get wrong now runs through a gated kernel (accounts.mjs), inlined verbatim into the live page:
- Integer pence throughout — no float ever touches money.
- The personal-allowance taper above £100,000 (reduced £1 per £2, gone at £125,140) — the old inline maths hard-coded the full £12,570 and told high earners they owed thousands too little. Fixed.
- Income tax 20 / 40 / 45 on taxable income · Class 4 NIC 6 % / 2 % · VAT return (MTD boxes 1/4/5/6/7) · VAT registration threshold — every rule a falsifiable, hand-checked worked example.
- The gate:
node --test accounts.test.mjs, then witness mutation-testing (48/50 mutants killed, 2 argued-equivalent). CI diffs the inlined kernel against the source, so the live tax maths cannot silently drift from the proven tax maths.
- Honest wire: it estimates on the 2026-27 rates as known at build (PA and bands are frozen to Apr 2028, so they match 2025-26). It is not a filing and not tax advice — confirm current thresholds with HMRC/gov.uk before you rely on a number or file a return.
What it is
A complete accounting autopilot for UK sole traders that runs entirely in your browser. No server. No subscription. No account to create. Open the file, use it, close the tab. Your data is yours.
- 📸 Receipt scanning — drop a photo, AI extracts vendor, amount, category, tax claimability
- 📊 Bank CSV categorisation — paste statement rows, get them sorted and ready to import
- 💷 Tax calculator — 2026-27 rates, NI Class 4, tapered personal allowance, all brackets (gated engine)
- 📋 MTD quarterly reports — Making Tax Digital compliant exports
- 🧾 Invoicing — generate, send, track, status-cycle
- 🤖 Dual AI — Claude API (most capable) OR local WebLLM (full privacy) OR offline guide
- 📝 Audit trail — every AI decision logged for HMRC defensibility
- 🔒 Truly sovereign — IndexedDB storage, no telemetry, no cloud, no lock-in
Replaces QuickBooks + accountant for a sole trader.
Why it's different
Most accounting software is a subscription that holds your data hostage. Cancel, lose access. Raise prices, you pay. Change terms, too bad.
FallAccount Elite is the opposite: one HTML file you own forever. It works offline. It works in 10 years when the vendor is gone. Your transactions never leave your machine unless you explicitly use the Claude API tier — and even then you provide your own key and data goes direct browser→Anthropic with no intermediary.
If you want to keep everything local, the WebLLM mode runs a 2-4GB model on your GPU. No API, no cloud, no traces.
The architecture
FallAccount runs on the 8+1 MACCubeFACE swarm pattern — a technique where instead of one monolithic AI call, the system routes work through 9 specialist agents:
α scaffold · β build · γ cache · δ run
ε gate · ζ observe · η score · θ format
Ω orchestrate
When you drop a receipt, it doesn't just "get processed." It gets:
- α scaffolded (what kind of document is this?)
- β built out (what fields should we extract?)
- δ run through extraction (actual vendor, date, amount)
- ε gated (is this claimable for a UK sole trader?)
- ζ observed (how confident are we per field?)
Result: every extraction comes back with per-field confidence scores. If the AI can't read the total clearly, it tells you rather than fabricating a number. Red dot = verify this. Green dot = trust it.
This matters because hallucinated numbers in accounting software are a nightmare waiting to happen. Most tools ship without this architecture. FallAccount ships with it baked in.
Three AI modes. Your choice.
🔑 Claude API (most capable)
- Best accuracy, handles complex edge cases
- Tiny per-query cost (bring your own Anthropic key)
- Direct browser→Anthropic API — no intermediary server
- Required for receipt image scanning (vision)
🤖 Local WebLLM (full privacy)
- Runs entirely on your GPU via WebGPU
- Zero API cost, zero internet needed after first load
- 5 model choices: 1B lightweight → 7B powerful
- First load downloads the model (~0.7-4GB), cached forever
- Handles chat + CSV categorisation
- Not available for receipt vision (small models don't do images yet)
📖 Offline Tax Guide
- Built-in UK tax knowledge base
- Works with zero AI, zero internet
- Covers mileage, home office, phone, software, deductions, MTD, deadlines
You pick in ⚙ AI Mode. Auto mode (default) uses Claude if you've set a key, falls back to local if loaded, else the offline guide.
Tech
- Single HTML file. No build step. No npm install. No framework overhead. Open it in a browser.
- IndexedDB for transactions, invoices, business profile, and AI audit log. Origin-sandboxed to your browser.
- localStorage for preferences and API key (the only things that persist outside IndexedDB).
- WebLLM via esm.run dynamic ESM import — no packaging required.
- Claude API via direct browser fetch with
anthropic-dangerous-direct-browser-access header.
- ~1,750 lines of vanilla JavaScript + HTML + CSS. Zero dependencies. Zero bundler. Zero external state.
- Dark mode because I use computers at 6am.
Install
# It's one HTML file. "Install" is a strong word.
curl -O https://your-download-url/FallAccount-Elite.html
# or just double-click it from your downloads folder
No terminal needed. Double-click the file. Browser opens it. Done.
Setup
- Open the file. It works immediately with the offline tax guide.
- Click ⚙ AI Mode in the sidebar to pick your AI engine.
- For Claude: click 🔑 Claude Key, paste your Anthropic API key (from console.anthropic.com). Stored in localStorage. Never transmitted anywhere except direct API calls.
- For local AI: click 🤖 Local AI, pick a model, download (~2GB for the recommended Llama 3.2 3B). Cached forever after first load.
- Set up your business in the My Business page — trade, income, home hours, mileage. Used to personalise tax calculations.
- Start dropping receipts anywhere on the page. They process in the background.
Data sovereignty
What stays local
- All transactions, invoices, business profile: IndexedDB (your browser, your machine)
- API key: localStorage (your browser, your machine)
- Downloaded local AI model: browser cache (your browser, your machine)
- AI audit log: IndexedDB (your browser, your machine)
What goes over the network
- In Claude mode: your query + system prompt → api.anthropic.com → response back. That's it.
- In WebLLM mode (after model loaded): nothing. Your GPU does all the work.
- In offline mode: nothing.
What we track
- Nothing. No analytics. No telemetry. No error reporting. No cookies to anyone. No "anonymous usage data."
Export anything, any time
- Full JSON export includes transactions, invoices, business profile, and complete AI audit log
- CSV export for spreadsheet users
- Quarterly HMRC-compliant reports for MTD
- Individual audit log exports for HMRC defensibility
Delete everything
- 🗑 Delete All Data button nukes everything (except API key — delete that separately)
- Two-step confirmation so you don't lose work accidentally
About this build
I'm Simon Fallon. I'm an English AI builder based in Pattaya, Thailand, operating as ai-nativesolutions.com — part of the Sodor Group.
Eighteen months ago I couldn't code. Today I ship production AI systems as single-file sovereign tools. FallAccount Elite is one of fourteen recent builds in that ecosystem.
What I build
- Sovereign single-file tools — HTML + IndexedDB, no server, no subscription, no lock-in
- 8+1 AI swarm architectures — anti-hallucination by design, not guardrails
- Accounting, legal research, shadow work, sales automation, and whatever else needs the same pattern
- AI that does the work, not AI that talks about doing the work
What I don't build
- SaaS pricing schemes
- Dependencies on frameworks that will break in 6 months
- Tools that pretend AI is magic when it's just probability with confidence tracking
- Software you rent forever
The long version
FallAccount Elite exists because accounting software is broken.
The market is divided between (a) spreadsheets that are fine until they aren't, (b) "easy" cloud solutions that cost £15-30/month forever and hold your data hostage, and (c) proper accountants at £80-150/hour. Sole traders earning £20-50k/year get squeezed: too advanced for spreadsheets, too expensive for cloud plus accountant, too small for enterprise ERP.
This tool replaces most of that. One file. Does the receipt scanning, the categorisation, the quarterly MTD reports, the tax estimation, the invoicing. Uses AI where AI helps. Doesn't use AI where it's not needed. Tells you when it's not confident.
It's built on the principles I use for everything: notation-first architecture, single-file sovereignty, anti-hallucination by design, compression over accumulation. These come from eighteen months of figuring out what actually ships and what just looks good in a demo.
If you're a sole trader: use the tool. It's yours. If it saves you money, tell someone.
If you're a business that needs a tool like this built for your specific domain: contact me. I do the work. You get the file. It runs on your computer forever.
That's the deal.
License
Personal use: free and will stay free.
Commercial use/modification/redistribution: contact me.
Credits
Built with Claude (Anthropic), WebLLM (MLC AI), and the quiet confidence that most software is more complicated than it needs to be.
Part of the Sodor Group — sovereign tools for people who'd rather own than rent.
◊·κ=1
The standard endures.
