A 6 months probationary period still comes with eighteen months of breathing room attached. Probation ends at month six. Unfair dismissal protection starts at two years. The space between those two dates is where UK employers quietly fix their hiring mistakes. 

That space will close. For dismissals taking effect on or after 1 January 2027, the qualifying period for unfair dismissal will be six months (Great Britain; Northern Ireland differs, covered below). A probation period that runs for six months will end on the day protection begins. There will be no buffer left. Anyone you hire from now on will reach month six after the change, so for them that space will never open. 

This article covers the mechanics. Whether a statutory probation period exists in UK law, what the Employment Rights Bill proposed, what the Employment Rights Act 2025 enacted, and how the six-month line will change the way probation has to run. For the claims that never needed service at all, see unfair dismissal under two years. The probation mechanics live here. 

Is there a statutory probation period in UK law? 

No. There has never been a statutory probation period in Great Britain, Northern Ireland's separate system does not impose one either, and the Employment Rights Act 2025 did not create one. ACAS guidance is plain on the point: there is no legal requirement to have a probation period, and one can be any length. 

Probation is a contractual device. It usually brings three things. A shorter notice period while it runs. Scheduled review points. An option to extend. Those terms exist only if your contract contains them. None of them comes from statute. 

What probation has never done is switch off employment rights. Day-one protections apply throughout: discrimination, whistleblowing, and the automatically unfair dismissal reasons that need no service at all. Our guide to probationary periods and employer risk sets out how little shelter probation gives employers even under the two-year rule. The short-service exceptions are covered in detail in unfair dismissal under two years. 

So when a contract sets a 6 months probationary period, those six months carry legal meaning only where the contract gives them some. What changes in January 2027 is what happens the day after they end. 

The statutory probation period the Employment Rights Bill proposed 

The phrase statutory probation period entered everyday use because of the Employment Rights Bill, not because of any law in force today. Understanding the difference matters, because a lot of older commentary still describes a regime that never arrived. 

The Bill as introduced went further than the Act we now have. It proposed removing the qualifying period for unfair dismissal entirely, making protection a day-one right. To balance that, it provided for a statutory initial period of employment at the start of a job. Inside that window, employers would have been able to dismiss using a lighter process than a full fair-dismissal procedure. Commentators shortened the whole concept to statutory probation, and the name stuck. 

That design did not survive Parliament. The House of Lords voted against day-one unfair dismissal rights, and the compromise that reached the statute book swapped the structure for something simpler: a shorter qualifying period. The Employment Rights Act 2025 received Royal Assent on 18 December 2025 with no statutory probation period in it, and no light-touch dismissal process either. 

That is the verified position at publication. Probation in the UK remains entirely contractual. ACAS states directly that the Act does not affect probation periods, and that there is still no legal requirement to have one and no required length. The Act itself adds no statutory process inside probation and no separate dismissal standard for people on it. If you read commentary promising a statutory probation window with lighter dismissal rules, you are reading analysis of a Bill that was amended before it passed. For the full list of what the Act does contain, our Employment Rights Act 2025 SME summary walks through it measure by measure. 

What section 25 of the Employment Rights Act 2025 changes 

Section 25 of the Act makes two amendments that matter here. 

First, it amends section 108 of the Employment Rights Act 1996, substituting six months for two years as the qualifying period for unfair dismissal. 

Second, it removes section 124 of the 1996 Act, the provision that caps the compensatory award. Unfair dismissal awards will no longer be subject to that statutory ceiling. What the change means for exposure is covered in our guide to unfair dismissal compensation awards. 

The date is already fixed in law: commencement regulations made on 26 May 2026 bring section 25 into force on 1 January 2027, and the GOV.UK implementation timeline lists it. The six-month qualifying period and the uncapped award will apply wherever the effective date of termination falls on or after 1 January 2027, including where notice is given in 2026 and expires in 2027. A dismissal with an effective date of termination in December 2026 still sits under the two-year rule. The test is that date, not the date of the decision, the date notice is given or the hire date. Every employee with six months' service on 1 January 2027 is therefore covered from that day, whenever they were hired. For anyone with under two years' service, including an employee hired in mid 2026, that is new protection. In the last week of December, the statutory week of notice under section 97(2) can carry a dismissal without notice into January when service is counted, so we advise treating any such dismissal as falling under the new rule. 

Two supporting points belong in the same picture. Since 1 October 2026, the time limit for bringing most tribunal claims has been six months rather than three, for events on or after that date. And Northern Ireland runs its own system, where the qualifying period usually remains one year. 

The 6 months probationary period will end where protection begins 

Most UK probation periods run three or six months. The six-month version has always been the cautious choice. From January 2027 it will be the riskiest one, because it spends the entire unprotected window and leaves no margin for a late decision. 

Run the arithmetic on a typical hire. Take a new starter who joins on Monday 4 January 2027 on a six-month probation. Six months of continuous service complete on 3 July 2027. The final probation review, held in the last week as most are, sits days away from full unfair dismissal protection. Add the six-month claim window, and a mishandled decision made in early July can still become a tribunal claim six months later. 

Under the two-year rule, the same review would carry eighteen months of slack. A borderline hire could be given a second chance at month six, because the business would keep its low-risk exit route until month twenty-four. That option ends for every employee on 1 January 2027. Giving the benefit of the doubt will then cost the whole remaining window. 

Here is the most misunderstood mechanic of the six-month rule. Extending probation does nothing to the statutory line. A contractual extension to nine months, which is longer than the six-month total we advise for any probation, moves your notice terms. It does not move the law, and we advise it never moves the final decision past 19 weeks after the start date. The employee will still gain unfair dismissal protection at six months of service, mid-extension, whatever the paperwork says. An extension clause still has uses, which we come to below, but preserving the low-risk exit route will no longer be one of them. 

The notice trap at the six-month line 

The second mechanic catches employers who decide late and act fast. 

Section 86 of the Employment Rights Act 1996 gives an employee with at least a month's but less than two years' service a statutory minimum notice period of one week. Section 97(2) then does something less well known. If the employer dismisses without notice, the effective date of termination moves later by that statutory week when qualifying service is counted. 

Run the example again. Suppose the 4 January starter is drifting and the decision slips to the final review. On 30 June 2027 the employer dismisses with immediate effect, three days short of the line, and assumes the risk has ended with the job. It has not. The statutory week pushes the effective date of termination to 7 July 2027. The employee then has more than six months of qualifying service and can claim unfair dismissal. 

Paying notice instead of working it does not switch this off. A payment in lieu is still a dismissal without notice, so the statutory week still counts. 

Longer notice periods create the same problem from the other direction. If the contract gives a month's notice during probation and you serve it in week 23, the notice expires after the six-month point, and the effective date of termination lands with it. The employee crosses into protection while working their notice. 

The date the employee is told matters as well. In Gisda Cyf v Barratt [2010] UKSC 41, a dismissal without notice sent by letter took effect only when the employee read it or had a reasonable opportunity to, not when it was posted or delivered. The case was decided on the time limit for a claim, but the effective date of termination it settled is also the date the Act uses to count service. For notice, Newcastle upon Tyne Hospitals NHS Foundation Trust v Haywood [2018] UKSC 22 reached the same result unless the contract says otherwise. A letter to someone who is away is the uncertain route, and so is an email they are not reading. We advise delivering the decision face to face, with the dismissal letter handed over, or by email on a day you know they will read it, and giving the reason every time, because an employee who is not given one will usually invent their own. We also advise leaving a buffer before the six-month line, which the week 19 point below provides. 

The practical rule falls straight out of the mechanics. A probation dismissal is only clear of the six-month line if the notice attached to it has fully expired before six months of service complete. Working backwards from that, and leaving room for notice and any slippage, the decision point we advise is week 19. For the 4 January starter, week 19, which is 19 weeks after the start date, falls on Monday 17 May 2027, about seven weeks before the six-month line on 3 July. This is the piece most probation processes were never built to deliver, and it is where SME probation is likely to fail quietly: not in the quality of the judgement, but in the date it gets made. 

Three, six or nine months: what each probation length will be worth 

There is no required probation length, so every employer chooses one. That choice will decide how much of the unprotected window is spent watching and how much is left for acting. One scope note first. ACAS points out that probation periods usually apply to people with employee status. Agency workers and casual workers on zero-hours contracts are not likely to be employees. For everyone on your payroll as an employee, the arithmetic below applies. 

A three-month probationary period leaves the widest margin. The final review lands at three months, around week 13. Even with a month of contractual notice, the exit completes well before six months of service. It also keeps one option in reserve: more time to assess a borderline hire. Where the contract allows it, we advise a single extension of no more than three months, which takes the whole probation to six months at most. It must be agreed before the first period ends and confirmed in writing with a reason and an end date. We advise using it only if the final review and the decision are still done no later than week 19 and notice stays at the statutory week, which in practice makes the useful extension the six weeks between week 13 and week 19. 

A 6 months probationary period will spend the whole window. The review, the decision and the full notice period must all land before the line, which is why we advise a 19-week decision point and treat it as the working deadline. An extension clause on a six-month probation will no longer change the legal position at all, because anything it adds sits past the line. Under the three-month extension cap and six-month total we advise, a six-month probation has no room for one. 

A nine-month probation, or an extension pushed past month six, will run its final stretch with full unfair dismissal protection already in force. Under section 210 of the Employment Rights Act 1996, a month of continuous employment means a calendar month. Service accrues in calendar time, not hours worked, so a part-time employee reaches six months on the same date as a full-timer who started the same day. From month six the probation label will carry no legal weight. A dismissal at month eight will need a fair reason and a fair process, exactly as it would for any established employee. Probation past the line is a management tool, not a legal one. That is why we advise against any probation, extended or not, that runs past six months. 

Whichever length the contract picks, the statutory line stays where the Act put it. From January 2027, the choice is no longer how long you get. Six months is what you get. The choice is how much of it you leave yourself. 

How to run probation under the six-month rule 

We advise five adjustments, which follow from the mechanics above. They are contract and calendar changes, described in general terms rather than advice on any individual case. Build them into the contracts you issue from now. For staff already employed, a change to contract terms needs the employee's agreement. 

1. Decide by week 19. Hold the final probation review and take the decision by then, not at week 25, extension or not. That leaves about seven weeks for notice to expire, and for any slippage, before six months of service complete, with the statutory week accounted for. If absence, a reasonable adjustment, pregnancy or maternity leave means a review cannot fairly be held by then, take advice before any decision. 
2. Keep probation notice at one week. The statutory minimum under section 86 is one week after a month's service. A longer contractual notice period during probation drags the effective date of termination towards the line. Generosity here has a legal cost. 
3. Put reviews in the diary before the start date. Four weeks, three months, and the final review and decision no later than week 19, extension or not, each with a written outcome. A probation decision at week 19 is only defensible if the file shows what was expected, what was said, and what support was given. Conversations without paperwork carry no weight later. 
4. Use extension clauses for what they still do. An extension buys time to assess a borderline hire, up to the week 19 decision, and that judgement still has value. It must be in the contract, agreed before the original period expires, and confirmed in writing with a reason and an end date. What it will no longer do is keep a low-risk exit route open. We advise capping any extension at three months, and the whole probation at six months, with the final decision still no later than week 19. 
5. Treat fair process as the default from day one. Day-one claims exist regardless of service, and from month six the ordinary fairness rules will apply in full. If a capability concern is emerging, the discipline of a proper process is set out in our guide to capability procedures. Building the habit during probation costs little. Retrofitting it after month six costs a great deal more. 

The theme across all five is the same. Probation is still a label with a long grace period behind it. From January 2027 it becomes a project plan with a hard deadline. The employers who adjust are not the ones with the longest contracts. They are the ones whose calendars force a decision while the decision is still cheap to make. 

Where does your probation process stand? 

Every business with anyone on probation in 2027, including people hired before the change, will be running probation against the six-month line, whether its paperwork has caught up or not. If your contracts, review dates and notice terms were written for the two-year world, the gap is worth finding before your next probation review does. 

Frequently asked questions

Is there a statutory probation period in UK law?

No. There has never been a statutory probation period in Great Britain, and the 2025 Act did not create one. The Bill as introduced proposed a statutory initial period of employment, and that design did not survive Parliament. Acas confirms there is no legal requirement to have a probation period, so its terms exist only if your contract contains them.

What is the maximum probation period in the UK?

There is no required length, and Acas confirms a probation period can be any length. Probation periods usually run three or six months. For dismissals taking effect from 1 January 2027, a probation running past six months of service will carry no legal weight, because unfair dismissal protection will already apply. We advise against any probation running past six months.

What happens to a 6 months probationary period from January 2027?

It will end where protection begins. For dismissals with an effective date of termination on or after 1 January 2027, the unfair dismissal qualifying period will be six months, so a six-month probation spends the whole unprotected window. That reaches existing staff, not only new hires. The review, the decision and the full notice must all land before the line.

Can you extend a probation period?

Yes, if the contract allows it, the extension is agreed before the original period expires, and you confirm it in writing with a reason and an end date. An extension moves your notice terms, not the law: protection will still start at six months of service. We advise capping any extension at three months and the whole probation at six.

How long is a probation period in the UK?

No law sets a length, and most UK probation periods run three or six months. A three-month probation leaves the widest margin: the final review lands around week 13, well before unfair dismissal protection starts at six months' service for dismissals taking effect from 1 January 2027. Whatever the length, we advise taking the final decision by week 19.

How much notice do you need to give during probation?

The statutory minimum under section 86 is one week once an employee has a month's service, and we advise keeping probation notice at one week. Longer contractual notice drags the effective date of termination towards the six-month line. Paying in lieu does not avoid this, because section 97(2) adds the statutory week when qualifying service is counted.

The free HR Health Check takes under a minute and lets you know where your business stands, from hiring paperwork to dismissal risk, before the six-month line arrives on 1 January 2027.