ThisQuarter

ThisQuarter is a desktop app built with Wails for HMRC's Making Tax Digital for Income Tax. It keeps your digital records and submits your quarterly updates, annual adjustments, and final declaration directly to HMRC — built for sole traders, landlords, and the accountants who look after them.

Built and sold by Computify Limited, registered in England and Wales.

Current Status

The core filing engine and the macOS, Windows, and Linux builds are done — signed, auto-updating, and talking to HMRC's Making Tax Digital APIs. I'm onboarding early users for MTD, and building out the accountant multi-client workflow. New users start free for their first two quarterly submission cycles — create an account.

The Problem

From 6 April 2026, Making Tax Digital for Income Tax stops being optional. Anyone with self-employment or property income above £50,000 has to keep digital records and send HMRC four quarterly updates a year plus one final declaration — the return that replaces the old SA100 Self Assessment. The threshold drops to £30,000 in 2027 and £20,000 in 2028, pulling in millions more people.

That's a large, involuntary migration. Overnight, a spreadsheet and one annual return becomes five submissions a year through an approved piece of software. Most of the existing MTD tools are cloud accounting suites — subscription bookkeeping platforms where your National Insurance number, UTR, and full financial picture live on someone else's servers. For a lot of sole traders and landlords, that's far more product — and far more data exposure — than the obligation actually requires.

The Vision

ThisQuarter is deliberately narrow: do the MTD obligation well, and keep the data on the user's own machine.

It's a native desktop app, not a web dashboard. Your figures, National Insurance number, and UTR stay encrypted on your own computer. Only the submissions you explicitly choose to file are sent — to HMRC, never to us. There's no server holding your books. The pitch is simple: meet the legal requirement without handing your tax life to a SaaS vendor.

Core Product

Submit to HMRC

Quarterly updates, annual adjustments (BSAS), and the Final Declaration that replaces Self Assessment — sent directly to HMRC through the Making Tax Digital for Income Tax APIs, from the desktop.

Every income source

Self-employment, UK property, and foreign property, with either consolidated or fully itemised expenses. Year-end brings in the rest of the picture for crystallisation: employment/PAYE (including P60 and P11D), dividends, pensions, Gift Aid, and Marriage Allowance.

CIS

For subcontractors, ThisQuarter pulls the Construction Industry Scheme deductions that contractors have reported against you, so they're accounted for at year-end.

For accountants

Connect your Agent Services Account, invite and manage clients, and file for all of them from one place — a single desktop workspace instead of logging into a separate portal per client.

Import / Export

Bring figures in from Excel and CSV, with a review step before anything is submitted.

Technical Approach

The defining constraint is local-first with no central store of user financial data. That shapes everything.

The desktop app — Wails (Go + Next.js)

The app is built with Wails: a Go core packaged with a Next.js frontend into a single native binary. Go handles the HMRC integration, encryption, and licence validation; Next.js renders the UI. Wails gives me a genuinely native, self-contained desktop app — no bundled Chromium, no Electron footprint — from one Go + TypeScript codebase, with signed builds for macOS (Intel & Apple Silicon universal), Windows 10/11, and 64-bit Linux. It checks for updates automatically and prompts when a new version is available.

Local, encrypted storage

Records, identifiers, and working figures are held encrypted on the user's own disk. The app only reaches the network to (a) submit to HMRC and (b) validate a licence key — nothing else leaves the machine.

The website — Next.js, Stripe & licensing

The marketing site and dashboard are a separate Next.js app. It owns everything the desktop app deliberately doesn't: Stripe handles subscriptions and billing, and on successful payment the site issues the licence key that unlocks the app. The two are decoupled — the desktop app only ever phones home to validate that key, never to sync financial data.

API deployment — Ansible & Cloudflare

The backing APIs are deployed with an Ansible playbook that provisions and configures the servers reproducibly. Everything sits behind Cloudflare, which proxies traffic and hides the origin IP so the real servers aren't directly reachable or trivially mapped.

Build hardening & code signing

An unsigned desktop binary gets flagged as malware the moment a user tries to open it, and getting a tax app to install cleanly on every OS turned out to be a real piece of engineering.

The Windows build is compiled through Wails with obfuscation, then code-signed with Azure Trusted Signing (Microsoft's cloud signing service) as the very last step — signing has to come after obfuscation, or the obfuscator would invalidate the signature. That Authenticode signature is what removes the SmartScreen "unknown publisher" warning and lets the download build reputation over time. macOS builds are signed and notarised under an Apple Developer identity so Gatekeeper doesn't block them.

The more interesting decision was what not to do. I deliberately don't pack the binary with a protector like Themida or VMProtect: heavy packers trip Windows Defender and SmartScreen heuristics and get you false-positive "malware" flags — exactly the outcome signing is meant to avoid. And because the real licence enforcement lives server-side, client-side packing would buy almost nothing anyway. Obfuscate lightly, sign properly, keep the trust signals clean.

HMRC integration

Authentication happens on HMRC's own pages — Government Gateway for individuals, Agent Services Account for accountants — so credentials are never entered into ThisQuarter itself. From there the Go core drives HMRC's MTD for Income Tax obligations, submissions, and declaration endpoints.

Pricing

• Free trial — every new account gets its first two quarterly submission cycles free.
• Sole traders — a low flat monthly fee after the trial.
• Accountants — tiered by client count, on annual agreements.
• Final Declarations — priced per filing.

Current pricing lives at thisquarter.co.uk/pricing.

Why I Built This

MTD for Income Tax is a rare thing: a hard, government-mandated deadline that forces millions of people to adopt new software whether they want to or not. Most of the answers being sold to them are heavyweight cloud accounting subscriptions that want to own the whole relationship — and the whole dataset.

I wanted the opposite. A focused tool that does exactly what the law requires, runs on your own machine, and treats your tax data as yours. ThisQuarter is that: submit your quarters, file your declaration, and keep your numbers off everyone else's servers.

ThisQuarter is third-party software for HMRC's Making Tax Digital. It is not affiliated with or endorsed by HMRC, and it is not tax advice.