The payrolling benefits spec is out. How my predictions did

By Sam Brown · 24 September 2026 ·5 min read ·Figures checked 24 September 2026

In short

HMRC published the 2027/28 RTI pack on 16 September 2026, on the normal RTI date, six weeks before the Budget I said it would arrive with.
Of ten predictions: five right or holding, two half right, three still open.
The one thing I got wrong: voluntary payrolling does use the new fields. Two of them, plus real-time Class 1A.
Field count was close. I said about 32 items with 18 new. It is 35 with 21 new.

On this page

What landed
The scorecard
The thing I got wrong
Where the counts landed
Updated predictions
Sources

In August I wrote a post predicting what the payrolling benefits spec would look like 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#

Predictions are mine and clearly marked. This isn’t tax advice.