Case Study — Internal Product
A tax compliance platform built for two April 2026 deadlines
We built our own end-to-end tax compliance platform covering MTD ITSA, CT600, and VAT — integrated with 17 HMRC APIs across 60+ endpoints, with 100% coverage of all HMRC-listed software features. UK-hosted, multi-client, and compliant before the deadline.
100%
HMRC feature coverage
17
HMRC APIs integrated
3
Tax types covered
The Compliance Landscape
Two simultaneous deadlines, both requiring new software
April 2026 brought two distinct changes to UK tax compliance — both requiring software that, until recently, either did not exist or was only available as part of expensive, over-engineered accounting suites.
MTD ITSA — Making Tax Digital for Income Tax
From April 2026, sole traders and landlords earning over £50,000 must submit quarterly digital returns to HMRC. That threshold falls to £30,000 in 2027 and £20,000 in 2028. The reporting obligation is ongoing: four quarterly updates per year, an annual submission, and a final declaration — all via recognised software.
CATO Closure — CT600 Corporation Tax
HMRC’s free Company Accounts and Tax Online (CATO) portal closed permanently on 31 March 2026. Every limited company — around 4.9 million in the UK — previously relying on the free portal to file their annual CT600 now needs commercial software. The filing itself is unchanged: the same annual CT600 in iXBRL format. Only the free channel disappeared.
The existing market did not serve either need well. Full accounting suites — Xero, QuickBooks, Sage — carry payroll modules, inventory tracking, and multi-currency functionality that most sole traders and small companies will never use, at prices that reflect that scope. Bridging tools address the MTD technical requirement but leave all the actual bookkeeping and categorisation work to the user.
Accountancy practices faced an additional dimension: no single tool gave them multi-client management across both ITSA and CT600 obligations. Managing a portfolio of clients through both deadlines meant either stitching together separate products or continuing to rely on spreadsheets for tracking.
We built the platform to close those gaps.
What Was Built
End-to-end tax compliance — from upload to submission
The platform covers the full pipeline: document ingestion, automated processing, bookkeeping, HMRC submission, and client management — without requiring any accounting knowledge from the end user.
MTD Income Tax
Full quarterly reporting workflow for sole traders and landlords. Four quarters per year, cumulative submission, with end-of-period statements and final declarations.
- ✓ Quarterly updates — self-employment, UK property, foreign property
- ✓ Annual submission with capital allowances
- ✓ Final declaration and HMRC tax calculation
- ✓ Amendment workflow for submitted periods
- ✓ 15 additional income sources (interest, dividends, pensions, capital gains, and more)
Corporation Tax
Direct replacement for CATO. Annual CT600 filing with iXBRL-formatted accounts and tax computation, submitted to HMRC via Government Gateway.
- ✓ Full CT600 computation with iXBRL output
- ✓ Direct Government Gateway submission
- ✓ PDF export for client records
- ✓ Historic filing archive (CATO migration)
- ✓ Individual, partnership, and LLP entity types
MTD VAT
MTD-compliant VAT returns with all nine boxes prepared from bookkeeping data and submitted directly to HMRC.
- ✓ Nine-box return prepared from bookkeeping
- ✓ Direct HMRC VAT submission
- ✓ VAT obligation and deadline tracking
- ✓ Submission history and audit trail
The full pipeline
Every step from raw document to HMRC confirmation is handled within a single platform.
Upload
Receipts, invoices, bank statements — photo, PDF, CSV, or Excel. From phone, email, or browser.
Extract
Every line item extracted and matched to the correct HMRC category. No manual data entry.
Bookkeeping
Income and expenses maintained in real time, feeding directly into tax calculations.
Submit
Quarterly update, VAT return, CT600, or final declaration — sent to HMRC with a full audit trail.
Coverage & Technical Depth
Built against the HMRC software listing — not around it
HMRC publishes a recognised software listing specifying which features each product supports. The platform was built to cover every item on that listing, not a subset.
10/10
Software Features
Full HMRC listing coverage
3/3
Business Types
Individual, partnership, LLP
15/16
Income Sources
All except partnership (HMRC API pending)
60+
API Endpoints
Across 17 HMRC APIs
Software features (10/10)
Every capability listed on the HMRC recognised software listing, implemented and tested.
Record keeping — transactions, document extraction, double-entry bookkeeping
Bridging software — CSV and Excel import with auto-column detection
Submit quarterly update — cumulative from 2025–26 onwards
Submit annual update — capital allowances, trading income allowance
View tax calculation — income tax, NICs, total liability
Make a final declaration — full finalisation workflow
View previously submitted updates
Amend quarterly update
Amend annual update
Claim to reduce payments on account
HMRC API integration
17 individual HMRC APIs integrated across the platform, covering every tax obligation supported.
Business Source Adjustable Summary (BSAS) API
Business Details API
Individual Calculations API
Obligations API
Self-Employment Business API
Property Business API
Savings Accounts API
Dividends Income API
Pensions Income API
State Benefits API
Other Income API
Employments API
Foreign Income API
Insurance Policies API
CGT Residential Property API
Reliefs API
Deductions API
Additional platform modules
Bookkeeping
Built-in income and expense tracking feeding directly into tax calculations. No separate bookkeeping tool required.
Practice management
Accountants manage full client portfolios from a single dashboard — obligation tracking, document collection, and filing status across all clients.
Automated communications
Clients receive deadline reminders and can reply with attachments that are processed directly into their account — no manual intake step.
Who Benefits
A single platform for every affected user type
Sole traders
Self-employed individuals earning over £50,000 who must file under MTD from April 2026. Upload documents from a phone, review extracted data, and submit without any accounting knowledge.
Landlords
UK property landlords with qualifying rental income. Property income submitted quarterly alongside any self-employment income — in one place, not two separate products.
Limited companies
Every limited company previously relying on CATO for free CT600 filing now needs commercial software. The platform replaces CATO directly, with the same iXBRL format output and Government Gateway submission.
Accountancy practices
Multi-client management across ITSA quarterly reporting and CT600 annual filing. Automated document collection from clients. Obligation deadlines tracked across the entire portfolio from one dashboard.
Results
Delivered before the deadline
100%
HMRC software feature coverage across all supported tax types
3-in-1
MTD ITSA, CT600, and VAT in a single platform — replacing 3–4 separate tools
Zero
Data leaves UK servers — all processing and storage on UK-hosted infrastructure
April 2026
Compliant before the MTD ITSA and CATO closure deadlines
The project demonstrates the scope of what a dedicated HMRC integration effort requires. Building across 17 APIs and 60+ endpoints, covering every item on the HMRC recognised software listing, and delivering practice management alongside direct filing capabilities is not a bridging exercise. It is a full platform build.
For accountancy practices in particular, the consolidated view removes the coordination overhead of managing dozens of clients across separate tools. A practice that previously tracked client deadlines in a spreadsheet and maintained separate products for CT600 and ITSA can manage everything from a single interface — with automated document collection reducing the manual intake workload for each client.
For individual filers, the full pipeline — from photo of a receipt to HMRC confirmation — means no accounting background is needed to remain compliant.
Learn more
The platform is available to sole traders, landlords, limited companies, and accountancy practices
Details of what the platform covers for each user type — features, workflow, and how to get started — are on the solutions page.
View the tax & accountancy solution →Need HMRC-compliant tax software?
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