UK Payroll Cost Calculator — connector documentation

MCP endpoint: https://uk-payroll-costs.connectorbay.com/mcp
REST API: POST https://uk-payroll-costs.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://uk-payroll-costs.connectorbay.com/openapi.json
Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
Authentication: none required. An optional Authorization: Bearer <key> raises rate limits.
Health: https://uk-payroll-costs.connectorbay.com/health · Tool schemas: https://uk-payroll-costs.connectorbay.com/tools.json
Publisher: Unify Dynamics LLC · connectorbay.com/uk-payroll-costs · agent@connectorbay.com

What UK Payroll Cost Calculator is for

UK Payroll Cost Calculator turns the 2026-27 GOV.UK employer rates into exact numbers a small business can plan with. employer_ni and employee_ni compute Class 1 National Insurance for a weekly, monthly or annual pay period and show every band, including the zero-rate reliefs for apprentices under 25 (category H) and employees under 21 (category M). employment_allowance_offset applies the GBP 10,500 Employment Allowance against a liability. nmw_check compares an hourly rate, or a salary and weekly hours, with the National Minimum or Living Wage for the worker's age and apprentice status on a given date. apprenticeship_levy applies the 0.5% rate and GBP 15,000 allowance to a pay bill. employer_cost_of_hire adds employer National Insurance and the minimum employer workplace-pension contribution to a salary. ni_thresholds_for_period and rates_reference return every figure with its source, tax year and how well it was verified. PAYE income tax, student loans and NIC categories beyond A, B, C, H, J and M are not modelled.

Ask your assistant things like:

"What employer National Insurance do I pay on GBP 3,000 of monthly pay for an employee?"
"How much does a GBP 32,000 employee really cost me a year including employer NIC and the minimum pension?"
"My employer NIC bill for the year is GBP 14,000: how much does the Employment Allowance take off?"
"Is GBP 11.50 an hour enough for a 22 year old, and what is the minimum for a 19 year old in an apprenticeship's second year?"
"What are the monthly National Insurance thresholds and where do the figures come from?"

What it does

employer_ni: Employer Class 1 National Insurance for one pay period, with the band breakdown and the category letter used.
employee_ni: Employee Class 1 National Insurance for one pay period, with the band breakdown and the category letter used.
employment_allowance_offset: Apply the Employment Allowance (up to GBP 10,500 a tax year) against an employer Class 1 National Insurance liability.
ni_thresholds_for_period: Class 1 National Insurance thresholds and rates for a weekly, monthly or annual period.
nmw_check: Check an hourly rate, or a salary and weekly hours, against the National Minimum or Living Wage for the worker's age and apprentice status.
apprenticeship_levy: Apprenticeship Levy at 0.5% of the annual pay bill less the GBP 15,000 allowance.
employer_cost_of_hire: Salary plus employer National Insurance (with optional Employment Allowance) plus the minimum employer workplace-pension contribution for a role.
rates_reference: Every rate, threshold and allowance this connector uses with source URL, tax year and verification level.

Data sources

Reference data from official sources (gov.uk); every answer states its source, date and validity period.

What it is not

UK Payroll Cost Calculator is independent; not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Names of rails, schemes and standards are used only to say what a tool works with. It is read-only: it never sends, pays, files or signs anything for you, and it never looks up private individuals.

Not advice. General information only, not legal, tax, accounting or payment advice. UK Payroll Cost Calculator is an independent tool: it is not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Rates, thresholds and rules change; check the cited official source and confirm with a qualified professional before you rely on a result.

Built for: GB. Languages: English.

Tools

Reference & guides

employer_ni — Employer Class 1 National Insurance on one pay period at 15% above the secondary threshold (0% up to the upper secondary threshold for categories H and M). Use for "What employer National Insurance do I pay on GBP 3,000 of monthly pay?". Args: pay, period, category, on_date.

employee_ni — Employee Class 1 National Insurance on one pay period: 8% between the primary threshold and the upper earnings limit, 2% above (category A). Use for "How much National Insurance is taken from an employee paid GBP 3,000 a month?". Args: pay, period, category, on_date.

employment_allowance_offset — Apply the Employment Allowance (up to GBP 10,500 in the tax year) against an employer Class 1 NIC liability and show the wording of the eligibility rules. Use for "My employer NIC bill for the year is GBP 14,000: how much does the Employment Allowance take off?". Args: employer_nic_due, allowance_already_used, on_date.

ni_thresholds_for_period — Class 1 National Insurance thresholds (lower earnings limit, primary, secondary, upper secondary, upper earnings limit) and rates for a weekly, monthly or annual period. Use for "What are the monthly National Insurance thresholds this tax year?". Args: period, on_date.

nmw_check — Compare an hourly rate, or a salary and weekly hours, with the National Minimum or Living Wage for the worker's age and apprentice status on a date. Use for "Is GBP 11.50 an hour enough for a 22 year old?". Args: age, hourly_rate, annual_salary, weekly_hours, apprentice, apprenticeship_first_year, on_date.

apprenticeship_levy — Apprenticeship Levy: 0.5% of the annual pay bill less the GBP 15,000 annual allowance. Use for "What apprenticeship levy applies to a GBP 4,000,000 annual pay bill?". Args: annual_pay_bill, on_date.

employer_cost_of_hire — Annual cost of employing someone: salary plus employer National Insurance (less any Employment Allowance you have left) plus the employer pension contribution on qualifying earnings. Use for "What does a GBP 32,000 employee really cost me a year?". Args: annual_salary, pay_frequency, category, pension_applies, employer_pension_percent, employment_allowance_remaining, on_date.

rates_reference — Every rate, threshold and allowance this connector uses, with source URL, tax year and verification level. Use for "Which sources and tax year do your payroll figures come from?". Args: topic, on_date.

Conventions

Read-only. Every tool reads public data or computes; nothing is written anywhere and nothing about the user is stored.
Result envelope. ok: true with data, or ok: false with a structured error (bad_input, not_found, upstream_error). degraded lists optional sources that were unreachable.
Rate limits. Free tier 60 tool calls/minute and 300/day per user (keyed on the user identifier supplied by the host agent, else client IP); Pro keys raise this. Over-limit calls return HTTP 429 with Retry-After. initialize and tools/list are never counted.

Support

agent@connectorbay.com · connectorbay.com/uk-payroll-costs/support