UK Self-Employed NIC

UK Self-Employed NIC — connector documentation

• MCP endpoint: https://uk-self-employed-nic.connectorbay.com/mcp
• REST API: POST https://uk-self-employed-nic.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://uk-self-employed-nic.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-self-employed-nic.connectorbay.com/health · Tool schemas: https://uk-self-employed-nic.connectorbay.com/tools.json
• Publisher: Unify Dynamics LLC · connectorbay.com/uk-self-employed-nic · agent@connectorbay.com

What UK Self-Employed NIC is for

UK Self-Employed NIC calculates the National Insurance a sole trader or partner pays on self-employed profits. class4_nic applies 6% to profits between the lower profits limit (GBP 12,570) and the upper profits limit (GBP 50,270) and 2% above, with the band workings. class2_nic and small_profits_threshold_check show the weekly Class 2 rate (GBP 3.65 in 2026-27) and whether profits reach the small profits threshold (GBP 7,105) so that Class 2 is treated as paid, or fall below it where only voluntary payment is an option. total_nic_summary combines the two for a profit figure. mtd_start_check compares a qualifying income figure with the phased thresholds for Making Tax Digital for Income Tax (GBP 50,000 from 6 April 2026, GBP 30,000 from 6 April 2027, GBP 20,000 from 6 April 2028) and says whether the start date has passed. nic_thresholds_reference lists every rate and limit for 2025-26 and 2026-27 with GOV.UK source, retrieval date and verification label. Exact decimal arithmetic, local only, nothing stored or filed. Income tax is not calculated. General information only, not tax advice.

Ask your assistant things like:

• "I made GBP 30,000 profit as a sole trader in 2026-27: how much Class 4 National Insurance is that?"
• "My profit was only GBP 6,000: do I have to pay Class 2 National Insurance?"
• "What is my total Class 2 plus Class 4 National Insurance on GBP 60,000 of profit?"
• "My self-employment income was GBP 35,000 in 2025-26: when does Making Tax Digital for Income Tax start for me?"
• "What are the Class 2 and Class 4 rates and thresholds for 2025-26 and 2026-27, with sources?"

What it does

• class4_nic: Class 4 National Insurance on self-employed profits: 6% between the lower and upper profits limits and 2% above.
• class2_nic: Class 2 National Insurance: the weekly rate and whether profits reach the small profits threshold so that Class 2 is treated as paid.
• small_profits_threshold_check: Say whether profits reach the small profits threshold (GBP 7,105 in 2026-27) and so whether Class 2 is treated as paid.
• total_nic_summary: Combine Class 2 and Class 4 National Insurance for a profit figure, with the band workings.
• mtd_start_check: Say when Making Tax Digital for Income Tax applies for a qualifying income figure (phases from 6 April 2026, 2027 and 2028).
• nic_thresholds_reference: Return the Class 2 and Class 4 rates and thresholds with source, tax year, verification label and the Making Tax Digital phases.

Data sources

• https://www.gov.uk/self-employed-national-insurance-rates
• https://www.gov.uk/government/publications/rates-and-allowances-national-insurance-contributions/rates-and-allowances-national-insurance-contributions
• https://www.gov.uk/guidance/find-out-if-and-when-you-need-to-use-making-tax-digital-for-income-tax

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

What it is not

UK Self-Employed NIC 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 Self-Employed NIC 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

Calculate

total_nic_summary — Combine Class 2 and Class 4 National Insurance for a profit figure, with the band workings. Use for "What is my total National Insurance as a sole trader on GBP 60,000 of profit in 2026-27?". Args: profits, tax_year, on_date.

Reference & guides

class4_nic — Class 4 National Insurance on self-employed profits: 6% between the lower and upper profits limits and 2% above. Use for "How much Class 4 National Insurance do I pay on GBP 30,000 of profit in 2026-27?". Args: profits, tax_year, on_date.

class2_nic — Class 2 National Insurance: the weekly rate and whether profits reach the small profits threshold so that Class 2 is treated as paid. Use for "Do I have to pay Class 2 National Insurance on GBP 10,000 of profit?". Args: profits, tax_year, on_date, weeks.

small_profits_threshold_check — Say whether profits reach the small profits threshold (GBP 7,105 in 2026-27) and so whether Class 2 is treated as paid. Use for "My profits are GBP 7,105: do I reach the small profits threshold?". Args: profits, tax_year, on_date.

mtd_start_check — Say when Making Tax Digital for Income Tax applies for a qualifying income figure (phases from 6 April 2026, 2027 and 2028). Use for "My income was GBP 35,000 in 2025-26: when do I have to use Making Tax Digital for Income Tax?". Args: qualifying_income, income_tax_year, on_date.

nic_thresholds_reference — Return the Class 2 and Class 4 rates and thresholds with source, tax year, verification label and the Making Tax Digital phases. Use for "What are the self-employed National Insurance rates and thresholds for 2026-27 and where do they come from?". Args: tax_year.

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-self-employed-nic/support

UK Self-Employed NIC — Privacy Policy

Effective 29 September 2026. Unify Dynamics LLC ("we", "us"), Menlo Park, California.

What UK Self-Employed NIC is. UK Self-Employed NIC is a connector (an MCP server and REST API) that AI assistants call on your behalf: Class 2 and Class 4 National Insurance for sole traders by tax year, the small profits threshold and Making Tax Digital for Income Tax start dates. You talk to your assistant; the assistant sends us only the arguments needed for that one request.

What we receive. The arguments of each tool call, the technical headers needed to serve the request (an IP address or a client identifier supplied by the assistant, and a Pro API key if you have one), and standard server logs.

Nothing is stored. Every tool is a local calculation or a lookup against bundled reference data; no request is forwarded to any third party. Arguments are used for that one response and are not logged in request bodies, recorded, or used to train anything.

What we do not receive or store. We do not receive your conversation with the assistant, your name, contacts or account credentials, and we build no profile: each request is answered independently. Rate-limit counters (a client identifier and timestamps) are held in memory for at most 24 hours. Hosting access logs (IP addresses and request paths, not request bodies) are kept for up to 30 days for security and abuse prevention.

Sub-processors. None. Hosting: Vercel (United States regions).

Your rights. Because we store no personal data beyond short-lived logs, requests to access, correct or delete data are usually satisfied automatically; you can still contact agent@connectorbay.com and we will respond within 30 days. We do not sell or share personal information.

Children. UK Self-Employed NIC is a general-audience service operated by the adult using the assistant.

Changes. We will post changes here with a new effective date.

UK Self-Employed NIC — Terms of Service

Effective 29 September 2026. These terms govern use of the UK Self-Employed NIC connector ("the Service") operated by Unify Dynamics LLC ("we", "us").

1. The Service. UK Self-Employed NIC provides: Class 2 and Class 4 National Insurance for sole traders by tax year, the small profits threshold and Making Tax Digital for Income Tax start dates. It is accessed through an AI assistant or directly over MCP or HTTP, and is read-only.
2. General information, not professional advice. Output is general information and a drafting aid. It is not legal, tax, accounting, financial or payment advice, and it is not a filing or a payment instruction. General information only, not legal, tax, accounting or payment advice. UK Self-Employed NIC 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.
3. Independent. UK Self-Employed NIC is independent; not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Official names are used only to describe what a tool works with.
4. Sources and dates. Reference values state their source, date and validity period. Rules change: check the cited official source before you rely on a result.
5. Acceptable use. Automated use within the published rate limits is welcome. Do not use the Service to look up private individuals or to circumvent any authority's controls.
6. Availability. The Service is provided "as is" without warranty. We may change, limit or discontinue it at any time.
7. Data. Our Privacy Policy describes what we process. In short: your input is answered on our server and nothing is stored.
8. Pro keys. Optional Pro API keys are issued at our discretion, are personal to the holder and may be revoked for abuse.
9. Liability. To the fullest extent permitted by law, Unify Dynamics LLC is not liable for any loss arising from use of or reliance on the Service. Our total liability is limited to US $100.
10. Governing law. California law; venue in San Mateo County, California.
11. Contact. Unify Dynamics LLC · agent@connectorbay.com · https://connectorbay.com/uk-self-employed-nic

UK Self-Employed NIC support

Email agent@connectorbay.com. We answer within two business days.

• MCP endpoint: https://uk-self-employed-nic.connectorbay.com/mcp
• REST API: https://uk-self-employed-nic.connectorbay.com/openapi.json
• Live status: https://uk-self-employed-nic.connectorbay.com/health

When you report a problem, include the question you asked your agent, roughly when, and which agent you used (for example Claude, ChatGPT or Gemini). Never send us passwords, account numbers or ID numbers. UK Self-Employed NIC never asks for them.