If you've been following the Employment Rights Act 2025, you'll already know the headlines: zero-hours contracts are being reformed, workers get new rights to guaranteed hours, and the changes land in 2027. You'll probably also have heard the reassurance doing the rounds in the supply teacher market - that workers can simply opt out, and agencies that rely on flexible arrangements have little to worry about.
This article isn't a general introduction to the ERA 2025. It's specifically about the supply teacher agency model, and why that reassurance is more fragile than it looks. We'll cover three things that the general commentary misses: the aggregation problem that catches regularly-working supply teachers regardless of how many schools they cover, the reason the opt-out isn't the clean escape route it appears to be, and the unresolved question of who actually carries the compliance obligation in a multi-school agency arrangement. We'll also cover where the legislation does work in agencies' favour - because for genuinely ad-hoc sick cover, there is a clear and defensible path - and what the upcoming government consultation is likely to mean for how all of this gets resolved in practice.
The short version: most active supply teacher agencies are more exposed than they currently believe, and the window for getting ahead of it is 2026.
What the Act Actually Does The ERA 2025 received Royal Assent on 18 December 2025 and introduces four new obligations for workers on zero-hours and low-hours contracts: a right to be offered guaranteed hours, a right to reasonable notice of shifts, compensation for shifts cancelled at short notice, and protection from detriment or dismissal for asserting those rights. These provisions are not yet in force - they are expected to come into force in 2027, following a government consultation on implementation details anticipated in 2026.[1]
The centrepiece is the guaranteed hours obligation. After a reference period - anticipated to be 12 weeks, though the exact length will be set by secondary legislation - employers must offer a contract reflecting the hours a qualifying worker has actually worked during that period. A qualifying worker is someone employed under a zero-hours or low-hours contract who, during the reference period, worked a number of hours satisfying conditions to be specified in regulations as to number, regularity, or otherwise. The exact threshold for what counts as "low hours" will also be set in secondary legislation following the consultation.
Crucially, the worker doesn't have to accept. They can decline and remain on zero hours if they prefer. The Act doesn't force anyone into a guaranteed hours arrangement against their will.
This is where many agencies stop reading - and where the misunderstanding begins.
The Opt-Out Is Not What It Looks Like The most common assumption in the supply teacher market right now is that workers will simply decline the guaranteed hours offer, and life will continue as before. It's an understandable reading of the legislation, but it's wrong in two important respects.
First, a worker's declination is not permanent. The duty is triggered at the end of every reference period for as long as the worker remains a qualifying worker.[2] [3]
Second, the anti-avoidance provisions are serious. The ERA 2025 amends the ERA 1996 to make it automatically unfair dismissal if a worker is dismissed - or suffers any detriment - because they accepted or rejected a guaranteed hours offer, or because the employer sought to avoid its obligation to make one.[4]
The Aggregation Problem Here is the issue that most supply teacher agencies have not yet grasped, and it matters more than the opt-out question.
Supply teachers typically hold a single contract with their agency, under which the agency places them at different schools as work comes in. It is the agency relationship - not any individual school placement - that is the constant thread in their working life. The ERA 2025 reflects this directly: the Act explicitly provides that a worker need not have been engaged continuously throughout the reference period, and that hours worked across multiple assignments under the same agency contract all count toward the qualifying threshold.[5]
In practice, this means that a supply teacher working two days at one school, three days at another, and two days at a third - all arranged through the same agency under their single agency contract - has all of those days counted together toward the 12-week reference period total. No individual school sees the full picture. But the agency does, or should, because it is the agency that arranged every one of those placements.
For agencies whose teachers work supply as their primary income - which describes a significant proportion of any active supply register - this means that most of their regularly working teachers are almost certainly qualifying workers under the Act. The occasional retired teacher picking up a couple of days a month is a different matter. But a teacher doing four days a week, across a rotating mix of schools, managing their availability through one agency, is not a casual worker in any meaningful sense. The ERA 2025 is designed precisely for people in that position.[6]
This creates a compliance challenge that sits with the agency rather than with any individual school, and one that no individual school is equipped to manage.
Who Actually Has to Make the Offer This is where the supply teacher model gets structurally awkward under the new legislation.
Under the ERA 2025, the obligation to offer guaranteed hours to qualifying agency workers falls primarily on the end hirer - in this context, the school.[7] [8]
The supply teacher multi-hirer model is arguably the clearest case where the default end-hirer obligation is unworkable. A school that has used a supply teacher for four days during a term has no visibility of the other forty days that teacher worked at other schools through the same agency. It is not in a position to assess whether the teacher is a qualifying worker, let alone to make a meaningful guaranteed hours offer. The teacher's relationship - and the full picture of their working pattern - sits with the agency, not with any school.
The government is aware of this structural tension. The upcoming 2026 consultation on implementing regulations is expected to address multi-hirer scenarios specifically, and there is a reasonable prospect that the obligation will be switched to the agency in cases that match the supply teacher model.[9]
What the Act Gets Right About Supply Teaching It is worth being honest about where the legislation's instincts are sound, even from an agency perspective.
A supply teacher working four days a week through one agency, covering schools across a local area, is in a genuinely precarious position. No sick pay from the agency. No access to the Teachers' Pension Scheme. No certainty of work from one week to the next, and historically, rates of pay that have been compressed as agencies compete for school contracts.[10]
For agencies that care about the wellbeing of the teachers on their books, the guaranteed hours framework, properly managed, is not necessarily the threat it is sometimes presented as. The threat is administrative complexity and legal exposure for agencies that haven't thought through the implications - not the underlying policy intent.
Where the Fixed-Term Model Works Not all supply teaching is the same, and the Act makes meaningful provision for genuinely temporary engagements.
For genuinely ad-hoc cover - a teacher filling in for a colleague who has called in sick, for a day, a week, or perhaps a fortnight - the fixed-term "limiting event" exception applies cleanly.[11] [12]
This is already the right way to structure ad-hoc cover arrangements, for reasons that have nothing to do with ERA 2025 - clarity for the teacher about what they're taking on, clean documentation for the agency, no ambiguity about when the engagement ends. The Act reinforces rather than creates that need.
The limitation is that this model only resolves the compliance question for genuinely occasional and unpredictable engagements. For regularly working supply teachers, per-assignment fixed-term contracts document each placement correctly but don't address the underlying qualifying worker question - the hours are still aggregating across those placements under the single agency contract. The contract structure and the qualifying worker analysis are separate questions, and it's worth being clear-eyed about that distinction.
What Agencies Should Be Doing Now The provisions don't come into force until 2027, and the implementation details are subject to consultation. But 2026 is the preparation year, and the consultation that will set the detailed rules is expected before the end of it. Agencies that wait for the final regulations before considering their systems and processes will find the window very tight.
The practical questions worth working through now are straightforward. Do you have visibility, for each teacher on your books, of how many days they are working in total across all placements in any given 12-week period? Do your assignment documents correctly record the nature of each engagement - and specifically, for sick cover assignments, the limiting event that defines when the engagement ends? Do you have a workflow that generates per-assignment documentation, captures timesheet sign-off from the school, and creates a record that would be defensible if a teacher ever brought a tribunal claim?
For most agencies currently running this on spreadsheets, the honest answer to all three is no. That is not a criticism - the tools most supply agencies use were built for a different regulatory environment. But the environment is changing, and the time to start preparing is before the consultation lands, not after.
This is exactly the problem Hubbado is built to solve. Supply teaching is a high-volume, short-assignment model - a busy agency might process dozens of new placements every week, each needing its own contract, its own timesheet approval from the school, and its own invoices on both sides. That workflow is where most agencies are currently exposed: a contract that doesn't record the limiting event clearly, a timesheet that lives in an email thread, no aggregation of hours across placements. Hubbado handles the full cycle per assignment - contract out, timesheet approved, client and worker invoices generated automatically - fast enough to keep pace with the day-to-day tempo of supply placements, and with the audit trail that compliance requires. The hours aggregation picture across teachers follows naturally from that data.
The Broader Picture The ERA 2025 is the most significant overhaul of UK employment law in a generation. The supply teacher agency model - flexible, multi-hirer, agency-mediated, with workers operating under a single agency contract across many different end clients - sits squarely within the arrangements the legislation was designed to address. That doesn't mean the model is wrong or that agencies are acting in bad faith. It means the compliance obligations are real, and the administrative infrastructure most agencies currently have is not built to meet them.
The upcoming government consultation will clarify much of what is currently uncertain - the qualifying thresholds, the multi-hirer obligation question, what "regular" working means in practice for a teacher whose schedule varies term by term. We will publish a follow-up piece when it lands, covering what it means for supply agencies specifically and what the sector's consultation responses are likely to shape in the final regulations.
Hubbado is a back-office SaaS platform built for the high-volume, short-assignment model that supply teaching runs on - contracts, timesheets, and invoices handled automatically per placement, with the audit trail compliance now demands. If you're a supply teacher agency thinking through your position ahead of 2027, you can try the platform free here or get in touch to talk through your specific setup .
Government implementation roadmap, updated February 2026: https://www.gov.uk/government/publications/implementing-the-plan-to-make-work-pay-and-employment-rights-act . The zero-hours provisions are inserted as ss.27BA–27BT into the Employment Rights Act 1996 by ERA 2025 s.1 and Schedule 1, with commencement targeted for 2027 following secondary legislation. ↩︎ The duty to offer guaranteed hours under s.27BA(1) ERA 1996 (as inserted) applies at the end of every reference period for as long as the worker remains a qualifying worker - the cycle continues even where a worker rejects an offer and stays on zero hours. See Gowling WLG, "Employment Essentials: Employment law changes 2025 and beyond" (updated February 2026): https://gowlingwlg.com/en-gb/insights-resources/articles/2024/employment-law-changes-2024 ↩︎ The government's rejection of a simple standing individual opt-out is discussed in Lewis Silkin, "Employment Rights Bill unpacked: will guaranteed hours guarantee flexibility for both parties?" (March 2025): https://www.lewissilkin.com/en/insights/2025/03/13/employment-rights-bill-unpacked-will-guaranteed-hours-guarantee-flexibility-for-both-parties . The House of Lords proposed such an opt-out during the Bill's passage; the government declined to adopt it. ↩︎ ERA 2025 inserts automatic unfair dismissal protection into the ERA 1996 where the reason for dismissal is the worker's acceptance or rejection of a guaranteed hours offer, or the employer's attempt to avoid the duty to make one. Equivalent detriment protection applies to workers who are not employees. See Farrer & Co, "Employment Rights Act 2025: spotlight on changes to zero-hours contracts": https://www.farrer.co.uk/news-and-insights/employment-rights-bill-spotlight-on-changes-to-zero-hours-contracts/ ↩︎ s.27BA ERA 1996 (as inserted by ERA 2025 Schedule 1) provides that a worker qualifies "if — during the reference period the worker was employed by the employer under one or more worker's contracts (whether or not continuously)." The Explanatory Notes confirm this is intended to capture workers engaged through multiple sequential or parallel assignments under a single overarching agency contract. ↩︎ As of mid-2024, just over 90,000 workers in the education sector in England were on zero-hours contracts, the majority working as supply teachers: Schools Week, "Employment rights bill: Schools face zero-hour contract changes" (October 2024): https://schoolsweek.co.uk/employment-rights-bill-schools-face-zero-hour-contract-changes/ ↩︎ ERA 2025, Schedule 1 (inserting agency worker provisions into ERA 1996): the end hirer is the default party required to make guaranteed hours offers to qualifying agency workers. The government's rationale is set out in the Department for Business and Trade, "Application of the zero hours contracts measures to agency workers: government response" (March 2025), following a consultation that ran October–December 2024: https://assets.publishing.service.gov.uk/media/67c6b55072e83aab48866d92/government_response_application_zhc_agency_workers.pdf ↩︎ ERA 2025, Schedule 1: reserve power enabling regulations to switch the guaranteed hours obligation from the hirer to the work-finding agency for specified categories of agency workers. See Lewis Silkin, "Employment Rights Bill unpacked: zero hours reforms extended to agency workers" (March 2025): https://www.lewissilkin.com/en/insights/2025/03/13/employment-rights-bill-unpacked-zero-hours-reforms-extended-to-agency-workers ↩︎ Government factsheet, "Zero hours contracts" (updated March 2026): "The regulations may apply differently for directly engaged and agency workers. In developing the regulations, the Government will consult on all of the zero hours contracts measures." https://assets.publishing.service.gov.uk/media/67e429cf2621ba30ed9776d1/zero-hours-contracts.pdf ↩︎ The Supply Network, "Your Pay": https://www.thesupplynetwork.org/your-pay-2 ↩︎ s.27BD ERA 1996 (as inserted by ERA 2025 Schedule 1) permits an employer to offer a fixed-term contract rather than a permanent guaranteed hours contract where there is a reasonable "limiting event" - a specific event whose occurrence ends the engagement. See Doyle Clayton, "Employment Law Guide 2026: Zero hours and low hours and agency workers" (January 2026): https://www.doyleclayton.co.uk/resources/news/employment-law-guide-2026-zero-hours-and-low-hours-and-agency-workers/ ↩︎ The return of an absent employee is explicitly cited in the Explanatory Notes to the Employment Rights Bill as the textbook example of a qualifying limiting event under what is now s.27BD ERA 1996. See also Doyle Clayton, op. cit. ↩︎
