HMRC have released their 2027/28 Real-Time Information (RTI) data items guide designed for software developers. This guide tells developers the fields that must be reported via RTI for the tax year.
The latest versions of HMRC’s RTI specifications and data items guide is essential reading for developers. In this regard, the final RTI specifications for 2027/28 were published on 09 September 2026 and updated with the data items guide and on 16 September 2026.
The RTI specifications and data guide highlight the new fields required for Phase 1, starting April 2027. This will see the following benefits mandated for processing via payroll:
- Cars and car fuel;
- Vans and van fuel; and
- Medical benefits
This is essential information for software developers who will design the functionality in their products which payroll professionals then need to populate with data. Further, this complete view of data fields gives developers an updated version which, in turn, updates our previous article.
One of the most significant factors in this release are the new RTI fields for Class 1A National Insurance Contributions (NICs) to allow both:
- The real-time calculation and reporting of Class 1A NICs on benefits included in Phase 1 (cars, vans and medical). These NICs will be payable with the monthly PAYE remittance: and
- The real-time calculation and reporting of Class 1A NICs on other benefits that are payrolled voluntarily, i.e. not in Phase 1 (other). These NICs will also be payable with the monthly PAYE remittance
A 'Class 1A NICs PBiKs Adjustment’ allows these values to be amended, if necessary.
For Bookkeepers
If all benefits are to attract the real-time calculation, reporting and payment of Class 1A, ICB understands the requirement to differentiate between Phase 1 benefits and non-mandated / voluntary benefits. However, what this means is that if an employer is payrolling benefits voluntarily, this will have to be indicated and we advise members to contact their supplier to ascertain how and where this will be done in their product.
If benefits are currently payrolled voluntarily, possibly this will be automatic.