2024 NI changes: Investment Zone Employer NICs Relief (IZENR)

As part of the governments introduction of reliefs for investment zones from April 2023, a new recycled list of additional National Insurance categories are introduced from 6th April 2024 to report Employers NIC reliefs.

The added NIC categories for Investment Zones (IZENR) are:


The package of tax reliefs available in Investment Zones has been designed to bring forward new investment by reducing the cost of doing business.

Employer National Insurance Contributions (NICs) is included in the wider Investment Zone initiative and a reduction in the rate of employer NIC’s is available for all Investment Zone tax site-based businesses for employees who are working in that area (where the conditions to claim the relief are met.

This change in rate applies a zero-secondary rate of employer NICs for employees’ earnings above the secondary threshold up to and including an upper secondary threshold equivalent to the Freeport upper secondary threshold, where the conditions to claim the relief are met. The balance of earnings above this upper secondary threshold will be charged at 13.8%.

The threshold values are yet to be confirmed although indicated as not being changed until April 2026.

The calculation of primary Class 1 NICs is unaffected.


  • The employee must be a new hire whose employment starts on or after 6 April 2022 and before the applicable sunset date.
  • The employee cannot have worked for that employer (or an employer connected to the employer) in the previous 24 months.
  • The employee will spend a minimum 60% of their working time in the Investment Zone tax site
  • Claim will expire 36 months from the employee’s start date.

Off-payroll workers – the relief can be claimed by the liable secondary contributor.

What if multiple NIC reliefs could apply?

Where several different NIC Category letters could be applied, the employer has discretion to choose the NIC Category letter which provides most benefit (such as apprentices under 25 or those under 21).

Contribution rates (based on 2023/2024)

Based on the 2023/2024 contribution rates (previously indicated as being frozen until 2026 but subject to change, with the added NI categories the following are expected:

Calculation diagrams

HMRC have issued diagrams to software developers to demonstrate how the NIC calculation works for each of the new Investment Zone NIC Category letters.

Employers and employees will pay Class 1 National Insurance depending on how much the employee earns. This is calculated at the associated rate between each of the appropriate thresholds.

The Software Developers communication can be downloaded:

PAYadvice.UK 12/8/2023

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