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    "id": "employment.ni.class4.main_rate",
    "name": "Class 4 National Insurance: main rate",
    "category": "employment",
    "jurisdiction": "GB",
    "unit": "percent",
    "value_type": "percentage",
    "currency": null,
    "cadence": null,
    "source_type": "act",
    "act_probe": {
      "verdict": "ACT-HOLDS",
      "provision": "section-15-3ZA-a",
      "probed": "2026-07-29",
      "source_url": "https://www.legislation.gov.uk/ukpga/1992/4/section/15/data.xml",
      "content_hash": "sha256:cd8b2efe2ef94e680f9a519fe25821c228d0299e8a319624dee7378021264bb1",
      "tokens": [
        "6%",
        "6 per cent"
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    "values": [
      {
        "value": "6%",
        "value_minor": null,
        "effective_from": "2024-04-06",
        "effective_to": null,
        "announcement_date": null,
        "enacted_date": null,
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          {
            "role": "legislation",
            "citation": "Social Security Contributions and Benefits Act 1992, c. 4 s. 15(3ZA)(a) (\"the main Class 4 percentage is 6%\")",
            "uri": "https://www.legislation.gov.uk/ukpga/1992/4/section/15",
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          {
            "role": "guidance",
            "citation": "https://www.gov.uk/self-employed-national-insurance-rates (Class 4 rates for 2026 to 2027)",
            "uri": "https://www.gov.uk/self-employed-national-insurance-rates",
            "retrieved": "2026-07-29T08:16:12Z",
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    "definitions": [
      {
        "from": null,
        "to": null,
        "text": "The main Class 4 percentage: the rate of Class 4 National Insurance charged on annual profits from self-employment between the lower and upper profits limits.",
        "instrument": "Social Security Contributions and Benefits Act 1992 s.15(3ZA)(a)"
      }
    ],
    "applicability": {
      "basis": "pay_period_start",
      "note": "Charged on the profits of the tax year, so the rate for the year of assessment governs rather than any payment date.",
      "article": "Social Security Contributions and Benefits Act 1992 s.15(1)-(3ZA)"
    },
    "scope_note": "s.15(3ZA) states that the main Class 4 percentage is subject to alteration under s.143 of the Social Security Administration Act 1992, so a Treasury order can change it without amending this text. The rate fell from 9% to 6% across 2024 by amendments to this provision.",
    "notes": "The checklist warned that this figure was drafted as the spelt form \"9 per cent\" and would need the percentage parser extending. The current text reads \"6%\", so the warning is spent: the digit form is what the Act now carries. WS6-ACT-CLASS-SWEEP.md records the probe. effective_from is read from the F-note on the archived section: \"Figure in s. 15(3ZA)(a) substituted (6.4.2024) by National Insurance Contributions (Reduction in Rates) Act 2024 (c. 5), ss. 1(3)(a), 3(1)\" — the amendment that made the main rate 6%.",
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        "role": "legislation",
        "citation": "Social Security Contributions and Benefits Act 1992, c. 4 s. 15(3ZA)(a) (\"the main Class 4 percentage is 6%\")",
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      {
        "role": "guidance",
        "citation": "https://www.gov.uk/self-employed-national-insurance-rates (Class 4 rates for 2026 to 2027)",
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        "retrieved": "2026-07-29T08:16:12Z",
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