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Employer NI ignores the under-21 and apprentice zero rates and the Employment Allowance #1918
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Thresholds for whoever models the under-21 and apprentice zero rates here. I checked these against the primary sources on 2026-09-30.
- 2026-27 (law): the UST and AUST are £967 a week (SI 2001/1004 reg 10(e)-(f)), or £4,189 a month and £50,270 a year (reg 11(3B)-(3C)). For a period that is a multiple of a week, reg 11(3B)(c)/(3C)(c) gives £50,270 / 52 per week, the same convention the model uses for the UEL.
- 2027-28 to 2030-31 (announced, not yet legislated): the Budget 2025 policy paper says "the UST and AUST thresholds will remain aligned to the National Insurance contributions UEL at £967 per week up until the 2030 to 2031 tax year" (HMRC). Budget 2025 para 4.111 covers "other employer NICs relief thresholds aligned with the UEL".
- The veterans' UST is enacted only through 2027-28 (NICA 2022 s.6(4)(e)-(f) and s.8(2), as amended by SI 2026/231 reg 6).
- The freeport and investment zone UST is £481 a week for 2026-27 (HMRC rates page); I found no announced value for later years.
#1959 freezes the UEL itself through 2030-31. Tying new UST and AUST parameters to it would keep them aligned.
ni_class_1_employerapplies the full employer rate (15% from 2025-26) above the secondary threshold to every earner aged 16 or over. The model does not implement:is_apprenticeexists, but NI does not use it.So
ni_employeris overstated for under-21s and young apprentices, and gross of the Employment Allowance.policyengine-uk-datacalibrates weights to OBR "Class 1 Employer NICs" using this model'sni_employer(targets/sources/obr.py,obr/ni_employer). Any fix interacts with calibration.Found while fixing #1894 (PR #1895). There, the property test checks the statutory s.9 amount only from age 21, because of this gap.