# The payrolling benefits spec is out. How my predictions did
> In August I predicted what HMRC's 2027/28 payrolling spec would look like. It landed on 16 September 2026. Ten predictions scored, plus the one thing I said that was wrong.
- Author: Sam Brown (Payroll Explained)
- Published: 2026-09-24
- Tags: benefits in kind, payrolling, RTI, FPS, Class 1A, payroll software
- Canonical: https://payrollexplained.uk/blog/payrolling-benefits-spec-is-out/
---
In August I wrote [a post predicting what the payrolling benefits spec would
look like](/blog/benefit-in-kind-changes-2027-28/) before HMRC published it.
On 16 September 2026 HMRC published it. This post scores the predictions.
The spec itself, explained field by field, is coming in a separate post.
16 Sep 2026pack published, same date as last year's
35benefit data items (I said ~32)
21of them new (I said ~18)
2fields for voluntary payrolling (I said none)
## What landed
- **16 September.** "Real Time Information internet submissions: 2027 to
2028 technical specifications": the RIM v2.0 zip, a changes document and
the data item guide v1.0. Test service from October 2026, live from March
2027.
- **16 September.** HMRC told stakeholders (ICAEW and PAYadvice both
reported it, I haven't found it on GOV.UK) that employers can keep
globally mobile employees on P11Ds, and that Class 1A on voluntarily
payrolled benefits must be done in real time too.
- **23 September.** Annex 3 of the guidance, the field list I based the
August post on, gained "Fuel type". A week after the schema that already
required it.
## The scorecard
| # | What I said in August | What happened | Score |
|---|---|---|---|
| 1 | Spec lands with the Autumn Budget 2026 cycle, and it's Annex 3 plus validation rules | Landed 16 September, on the normal RTI date (last year's pack was 16 September 2025), six weeks before the 28 October Budget. Content is Annex 3 plus four fields that aren't in Annex 3, plus 36 business rules. | Mostly right |
| 2 | Class 1A paid with the normal monthly PAYE, same reference, 19th/22nd | Nothing official on references. But the corrections examples say underpaid Class 1A "is added to the employer's PAYE bill", and the EPS didn't get a single new field, so there's no separate stream to pay into. The reference chapter still promises an update "in the first half of 2026". | Looks right, not in writing |
| 3 | P46(car) retired for payrolled cars | Not mentioned anywhere in the pack or the September guidance. | Open |
| 4 | The Class 1A adjustment fields grow | One box became two, period and year to date. They also changed meaning: the guide now says the box holds an *adjusted benefit value*, not a NIC amount. | Right, for the wrong reason |
| 5 | End-of-year update is a revised final FPS, not a new submission type | The 31 July guidance says revise the final FPS, and the RIM has the same three message types as before. The deadline is still "expected to be before 19 July". | Right |
| 6 | First spec under-specifies negatives and leaver corrections | Negatives are answered by the schema, without a word of guidance: every in-period value is signed, every year-to-date value has a floor of 0.00. Leavers: the chapter still says "this guidance will be updated at Autumn 2026". | Half right |
| 7 | Phase 2 slips or gets pruned | Nothing about phase 2 in the pack. Still April 2028 on paper. | Open |
| 8 | Loans and living accommodation stay voluntary well beyond 2028 | Reaffirmed on 16 September, "until further notice". On 4 September HMRC added a voluntary-accommodation example to the guidance. | Holding |
| 9 | P11D(b) redesigned for 2027/28, announced late | Nothing. The data item guide just says non-payrolled benefits go "via the P11D(b) process". A third group now uses it: globally mobile employees. | Holding on "late" |
| 10 | A payrolling and Universal Credit story surfaces in 2027/28 | Too early. | Open |
Five right or holding, two half, three open. Then there's the thing I got
wrong.
## The thing I got wrong
In August I said "voluntary payrolling of non-mandated benefits won't use the
new FPS fields", and built a "three regimes at once" point on it. That came
straight from the guidance, which still says today:
> The extra Real Time Information (RTI) data fields will not be included in
> the voluntary service.
The pack says otherwise. Data items 354 and 355 are the period and
year-to-date totals of "all other (non-mandated) payrolled benefits". And
the business rules make them the only way to carry on doing what voluntary
payrollers do today: if you send item 60 (benefits taxed via payroll), the
Benefits block must be present, or the FPS is rejected with error 7959.
Add the 16 September announcement that voluntary benefits get real-time
Class 1A, and the picture is simpler than I predicted, not messier. Two
regimes: everything payrolled goes through the new block with Class 1A, and
everything else is a P11D.
## Where the counts landed
My working
The guide's benefit items run 255 to 280 (26 items), 290 to 292 (3) and
350 to 355 (6): **35**. Fourteen carry a "(Prev. xxx)" note pointing at an
old car field, so **21 are new**. August said "about 32 fields, 14 already
in RTI, roughly 18 new". The 14 was right. The three I missed are the two
voluntary totals and the year-to-date twin of the adjustment box.
## Updated predictions
The open ones from August stay open (P46(car), phase 2, P11D(b), Universal
Credit). New ones, with the reasoning to follow in the spec post:
| # | Prediction | Confidence |
|---|---|---|
| 11 | The guidance line saying the voluntary service won't get the extra RTI fields is rewritten before April 2027 | High |
| 12 | The Class 1A adjustment items get a new description in a data item guide v1.1 | High |
| 13 | There's a RIM v2.1 or v3.0 before go-live | Medium-high |
| 14 | Class 1A ends up on the ordinary PAYE charge with no separate reference | Medium-high |
| 15 | The most common rejection in April 2027 is 7959, from voluntary payrollers on unchanged software | Medium |
## Sources
- [Real Time Information internet submissions: 2027 to 2028 technical specifications (GOV.UK, 16 September 2026)](https://www.gov.uk/government/publications/real-time-information-internet-submissions-2027-to-2028-technical-specifications)
- [Mandatory payrolling of benefits in kind: interim guidance (updated 23 September 2026)](https://www.gov.uk/guidance/draft-guidance-and-legislation-to-aid-preparation-for-reporting-benefits-in-kind-in-real-time) and [its change history](https://www.gov.uk/guidance/draft-guidance-and-legislation-to-aid-preparation-for-reporting-benefits-in-kind-in-real-time/updates)
- [ICAEW: Globally mobile employees can be excluded from mandatory payrolling (September 2026)](https://www.icaew.com/insights/tax-news/2026/sep-2026/globally-mobile-employees-can-be-excluded-from-mandatory-payrolling)
- [PAYadvice: Payrolling 2027, Class 1A to apply to both mandatory and voluntary items (17 September 2026)](https://payadvice.uk/2026/09/17/payrolling-2027-class-1a-to-apply-to-both-mandatory-and-voluntary-items/)
- [The August post this scores](/blog/benefit-in-kind-changes-2027-28/)
*Predictions are mine and clearly marked. This isn't tax advice.*