Built with Claude.
Runs on Claude.
Integrates everywhere.
AccountsOS is all-in on the Claude ecosystem. MCP server, Desktop skill, Cowork plugin, and a chat interface powered by Claude Sonnet 4. UK founders who live in Claude will feel right at home.
Claude MCP Server
LiveQuery your books directly from Claude Desktop
Install the AccountsOS MCP package and connect your books to Claude Desktop. Ask questions in plain English, create transactions, check deadlines — all without leaving Claude.
The MCP server gives Claude direct read and write access to your AccountsOS data via a secure API. One install, permanent connection.
{
"mcpServers": {
"accountsos": {
"command": "accountsos-mcp",
"env": {
"ACCOUNTSOS_API_KEY": "your-api-key"
}
}
}
}Claude Desktop Skill
NewUK accounting knowledge + 8 slash commands
Download the AccountsOS skill for Claude Desktop. Gives Claude deep UK accounting knowledge and a set of slash commands for your most common accounting tasks.
Drop the skill file into your Claude Desktop skills folder. Claude immediately knows UK tax rules, HMRC deadlines, and how to structure your accounting questions.
accountsos-claude-skill/ Skill.md ← instructions + UK tax rules REFERENCE.md ← 2025/26 rates reference
Claude Cowork Plugin
Live6 commands, 4 skill packs, 13 API tools
The AccountsOS plugin for Claude Cowork. Deeply integrated — not just a link, but a full accounting copilot inside your Claude workspace.
Install from your plugins directory and Cowork immediately gets access to your books, with auto-firing skill packs that activate when you discuss tax, invoices, cash flow, or deadlines.
~/.claude/plugins/
accountsos/
plugin.json
tools/
skill-packs/Chat Powered by Claude Sonnet 4
LiveYour AI CFO is Claude under the hood
The AccountsOS chat interface runs on Claude Sonnet 4 with tool calling. When you ask 'how much did I spend on software?' or 'create a transaction for my AWS invoice' — that's Claude.
We chose Claude because it has the best reasoning for UK tax edge cases. Claude doesn't just retrieve data — it explains, advises, and catches things you'd miss.
You've spent £3,847.20 on travel this tax year. Breakdown: - Rail: £1,240.00 (19 trips) - Hotels: £1,890.00 (6 stays) - Taxis/Uber: £717.20 (34 trips) £2,890 of this is fully deductible for Corporation Tax purposes. The hotel stays include personal components — I've flagged 3 for your review.
Ask your books anything
Real questions UK founders ask AccountsOS every day. Claude doesn't just retrieve data — it reasons, advises, and catches things you'd miss.
“Log my AWS invoice — £127.50 inc VAT”
“What's my Corporation Tax estimate for this year?”
“When's my next HMRC deadline?”
“Am I on track for a profitable quarter?”
“Which expenses am I missing that I should be claiming?”
“Draft a payment reminder for invoice #INV-047”
We chose Claude deliberately
UK tax is genuinely complex. Corporation Tax marginal relief, VAT flat rate schemes, MTD obligations, director's loan rules — the edge cases matter. We tested multiple models and Claude handles them best.
Claude also has the best reasoning about ambiguous financial situations. When a receipt could be personal or business, Claude asks the right questions rather than guessing.
“MCP is an open standard developed by Anthropic. We didn't just integrate with Claude — we built on the protocol Anthropic created for exactly this kind of AI-to-tool connection.”
Model Context Protocol — the open standard for AI integrations
accountsos-mcpClaude Sonnet 4Model Context Protocol10 MCP + 13 APIYour books. In Claude. Right now.
Free to start. Connect your books in under 5 minutes. UK Ltd companies only — built for exactly your situation.
Free during Early Access. No credit card required.