Employer NI is zero for employees over state pension age #1894

Bug

ni_class_1_employer has defined_for = "ni_liable", and ni_liable is over_16 & ~is_SP_age. So employer (secondary Class 1) NI is zero for every employee at or over state pension age.

Calculator case on main (d2754dc), 2026-27, employment income £40,000:

Law

SSCBA 1992 s.6(3) ends only primary contributions at pensionable age:

(3) Except as may be prescribed, no primary Class 1 contribution shall be payable in respect of earnings paid to or for the benefit of an employed earner after he attains pensionable age, but without prejudice to any liability to pay secondary Class 1 contributions in respect of any such earnings.

Secondary contributions are due on earnings of "an earner over the age of 16" (s.6(1)(b)) with no upper age. HMRC NIM36001: "Employers of people over State Pension age are liable for secondary Class 1 contributions". The regulations the "except as may be prescribed" clause points to (SI 2001/1004 regs 28 and 29) adjust primary liability only.

At age 70 the employer should pay 15% × (£40,000 − £96 × 52) = £5,251.20, the same as at 35.

Fix

Gate ni_class_1_employer on a secondary-specific age condition (over 16), and keep ni_liable for primary Class 1, Class 2 and Class 4.