Sri Lanka Tax (lk-tax)

io.github.ShalomHunukumburav0.1.0Updated Oct 5, 2026

Exact, sourced Sri Lankan tax calculations: APIT, income tax, withholding tax, VAT and SSCL.

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Overview

AI-generated overview

Lets an assistant compute Sri Lankan APIT, income tax, withholding tax, VAT and SSCL from dated IRD rules instead of recalling rates.

What it does
Provides read-only calculation tools for Sri Lankan taxes: calculate_salary_tax for monthly APIT, calculate_annual_income_tax with band breakdown, calculate_withholding_tax across payment types, calculate_vat for adding or extracting VAT, check_vat_registration, calculate_sscl, check_sscl_registration, get_tax_rules and get_rule_history. Each calculation takes the applicable date, so results use the rules in force then, and every result includes a summary, exact decimal amounts and the IRD sources and rule version used.
When to use it
Useful when an assistant must answer Sri Lankan payroll, income tax, VAT or SSCL questions with exact, dated figures and citations, for example comparing APIT before and after the April 2025 band change. Not intended for lump sums, non-resident employees, VAT exemption classification or dates before 2023.
Requirements
Runs locally as a stdio process; the README says uv is required and the server is started with uvx lk-tax-mcp, or installed with pip. No authentication, environment variables or headers are declared, and the README states it needs no network access, files or credentials.
Before you install
Read-only and offline per the README, with no credentials requested. It is a calculator, not tax advice, and the README notes gaps such as lump sums, non-resident employees, VAT exemption classification and dates before 2023, so results should be checked against the cited IRD sources.

Installation

In SourceWeft

  1. Open Sri Lanka Tax (lk-tax) in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

lk-tax-mcp

Exact, sourced Sri Lankan tax calculations for AI assistants. An MCP server that lets Claude (or any MCP client) calculate APIT, income tax, withholding tax, VAT and SSCL from the official Inland Revenue Department rules for any date since 1 January 2023, instead of recalling rates from memory.

What it looks like

A real Claude Code session with only this server connected:

You: I'm paid Rs. 350,000 a month in Sri Lanka. How much APIT will my employer deduct this month, and how much was it before the April 2025 change?

Claude calls calculate_salary_tax twice, once for today and once for 31 March 2025, and answers (abridged):

This month: Rs. 32,500 APIT. The first Rs. 150,000/month is tax-free, then 6% / 18% / 24% / 30%. Source: IRD Notice PN/IT/2025-01 and APIT Tax Table No. 01 (2025/26). In force since 1 April 2025.

Before the change (to 31 March 2025): Rs. 52,500. Rs. 100,000/month tax-free, then 6% / 12% / 18% / 24% / 30% / 36%. Source: APIT Tax Table No. 01 (2023/24 & 2024/25).

So you now pay Rs. 20,000 less per month. This assumes it's your regular pay from your main job and you're a Sri Lankan tax resident; one-off bonuses or a second job use different tables.

The numbers come from the tool, the caveats come from the server's instructions, and every figure is traceable to an IRD document.

Why

Language models are confident about tax rates, and Sri Lanka's change often: in 2025 the salary tax bands were rebuilt, and in 2026 alone the SSCL threshold dropped, VAT on financial services rose to 20.5% and withholding tax was extended to more professions, all mid-year. A model recalling "the rate" is wrong for some dates and has no source to show. This server gives the model exact arithmetic over dated, sourced rules, built on lk-tax, which is tested against every row of the IRD's official APIT tables.

Install

Requires uv (uvx runs the server without a manual install).

Claude Code

bash
claude mcp add lk-tax -- uvx lk-tax-mcp

Claude Desktop: add to claude_desktop_config.json (Settings → Developer → Edit Config):

json
{  "mcpServers": {    "lk-tax": { "command": "uvx", "args": ["lk-tax-mcp"] }  }}

Any other MCP client: run uvx lk-tax-mcp as a stdio server, or pip install lk-tax-mcp and run lk-tax-mcp.

Tools

ToolAnswers
calculate_salary_taxAPIT to deduct from a month's salary (official Tax Table No. 01 amount)
calculate_annual_income_taxIncome tax for a year of assessment, with band breakdown
calculate_withholding_taxWHT on 11 payment types: thresholds, exemptions, grossing up
calculate_vatAdd VAT to a price or extract it from a VAT-inclusive price
check_vat_registrationDoes a business need to register for VAT?
calculate_ssclSSCL on turnover by activity (liable share × 2.5%)
check_sscl_registrationDoes a business need to register for SSCL?
get_tax_rulesRates, bands and thresholds in force on a date
get_rule_historyEvery change to a tax since 2023, with dates and sources

Every result includes a one-line summary, exact amounts as decimal strings, and the rule version used (effective_from, effective_to, IRD sources).

Design notes

  • Read-only and offline. Every tool is a pure calculation, annotated readOnlyHint and idempotentHint. No network access, no files, no credentials.
  • Dates are explicit. Each calculation takes the date it applies to (pay date, invoice date), so "what was it last year?" gets last year's rules.
  • Errors the model can act on. Bad input comes back as a tool error explaining what to fix (monthly_income must be a number, lk-tax covers 2023-01-01 onwards), not a generic failure.
  • Choices are enumerated. Payment types and SSCL activities are enums in the schema, each described, so the model picks a valid one.
  • Honest about gaps. The server instructions tell the model what isn't covered (lump sums, non-resident employees, VAT exemption classification, dates before 2023) and to say so rather than estimate.

Development

bash
uv syncuv run pytest                    # includes a test that launches the real command over stdiouv run mcp dev src/lk_tax_mcp/server.py   # explore the tools in the MCP Inspector

Built with the MCP Python SDK v2.

Disclaimer

Not tax advice. Results link to the IRD sources they come from, so you can check them.

License

MIT

Source: README.md at commit 7688c98

Tools

0
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Version history

1
  1. v0.1.0LatestOct 5, 2026