Probation under the six-month rule: the process that protects you before January

Somewhere in the UK this morning, an MD is signing an offer letter built on a template his solicitor drafted years ago. The probation clause reads the way it always has: six months, with a review at the end and a week's notice on either side. He has issued dozens of contracts carrying that clause and not one has ever come back to bite him. The wording has not changed. What the date inside it means is about to, and the change arrives on 1 January 2027.

What January actually changes

From 1 January 2027, the qualifying period for unfair dismissal falls from two years to six months, and the cap on the compensatory award is removed on the same day. Neither change phases in by hire date. Both apply by the effective date of termination. If an employee leaves your business on or after 1 January 2027 with six months' service behind them, they can bring an ordinary unfair dismissal claim regardless of when they joined. Government analysis puts around 6.3 million employees into scope on day one, which is everyone currently between six months' and two years' service with their employer.

That much has been widely reported, and if you have read our earlier piece on what the six-month rule changes for the hires you are making now, the headline will be familiar. This article is about the machinery underneath it, because the machinery is what quietly breaks a standard probation clause.

The week that moves your dates

Employment law adds statutory minimum notice when it calculates qualifying service. Once an employee has a month's service, that minimum is one week, and for unfair dismissal purposes the week counts towards service where the notice actually given falls short of it. In plain terms, an employee dismissed just inside the six-month mark can be carried over the threshold by a week they never worked.

Run the dates on a real hire. Someone starts on 3 August 2026. Their six-month probation ends on 3 February 2027, so the contract promises a review in the final week of January. An MD who holds that review on 28 January and decides the appointment has not worked out now has two bad options. Give a week's notice, and the effective date of termination becomes 4 February, past the six-month line, with unfair dismissal rights attached and no cap on the award. Dismiss on the spot instead, and the law adds the statutory week anyway, moving the effective date to 4 February all the same. The review the contract promises takes place after the point at which the decision could still be made safely.

The practical rule that falls out of this is blunt. A decision to end employment during probation has to be made early enough that, with the statutory week added, service still comes in under six months. On a six-month probation, that means the genuine decision point arrives around month five, weeks before the review your contract schedules. The clause you have been reusing for years is now working against you.

Why three months is now the right length

Progressa's standing recommendation, for contracts issued from this point on, is a three-month probation period, extendable once and only for a specific stated reason.

A three-month period forces the assessment to happen while every option remains open. If the answer is yes, you confirm the appointment and the employee gets certainty months earlier, which matters more to a good hire than employers tend to assume. If the answer is no, the decision can be made and given effect with a wide margin before any rights attach. And if the answer is genuinely unclear, an extension to a stated date for a stated reason still completes well inside the safe zone, statutory week included.

There is also a truer reason so many probation clauses run to six months in the first place. Under a two-year qualifying period, the probation end date carried no legal weight at all, so nobody had to think hard about where to put it, and six months became the number that lived on the template. The buffer that made the date harmless disappears in January. Once the date matters, it deserves to be chosen rather than inherited.

A review that earns its place in the diary

A probation process protects you only if it produces evidence, and from January, evidence carries the weight the two-year qualifying period used to carry for you.

That starts before the employee does. Put the standards in writing on day one, covering what good looks like at four weeks and what has to be true by the end of the period, in language specific to the role rather than lifted from the job advert. Diarise every review when the contract is signed, because a review that has to be remembered is a review that gets skipped in a busy month, and a skipped review is precisely the gap a tribunal will ask about. Hold the mid-point conversation even when things are going well, and write down what was said. Raise concerns in the week you notice them rather than saving them up. An employee who hears about a problem for the first time at their final review has a fair question about why nobody mentioned it in month two, and a tribunal will put the same question to you with rather more leverage.

Know which problem you are dealing with before you act on it, too. A new starter who cannot do the job and a new starter who will not follow reasonable instructions are different situations requiring different processes, and starting the wrong one is the error that costs most to unwind mid-stream. We have covered the capability and conduct distinction, and where employers confuse the two at length. During probation, the same distinction applies, just on a compressed clock. If nobody inside the business owns this rhythm week to week, that gap is exactly what hands-on HR support for growing businesses exists to close.

Extending probation: a tool with a signal attached

Only two letters really belong in a probation process. One confirms an extension. The other confirms that probation has been passed, and whether that second letter is needed at all depends on your contract wording: some contracts treat the period as passed automatically on expiry, while others require written confirmation, and if yours requires it, the confirmation deserves a diary date of its own, because an employee left in silence about their status has a fair question, and so does a tribunal reading the file later. The extension letter is the one with teeth, so its mechanics deserve care.

Getting those mechanics wrong voids the tool entirely. An extension is only available where the contract provides for one or the employee agrees to it, and it must be confirmed in writing before the original period expires. The confirmation needs a new end date, the specific reason for the extension, what has to change by the new date, and the support the business will provide to help that happen. An extension agreed after the period has lapsed carries no weight, because by then the employee has passed by default.

Then the part fewer advisers mention. An extension used as a routine option tells the employee something you may not intend to say: that the decision has effectively been made, and the paperwork is catching up with it. People read that signal accurately. Disengagement follows, and the extension produces the very outcome it was supposed to postpone. Used once, for a named reason and with genuine support behind it, an extension is a fair and useful instrument. Used as a default, it is a slow no.

After January, there is a second problem with the reflexive extension. Extending probation does nothing to delay unfair dismissal rights, because the right attaches at six months' service whatever the contract calls the period. An extension that runs past the six-month point changes the label on the employee and changes nothing about their legal position. Under the old regime that was a harmless oversight. Under the new one, it is a false sense of cover.

The hiring decision behind the probation process

A probation process can only assess the person your hiring process chose, and January raises the price of both. The earlier article on the six-month rule covers what the change means for recruitment decisions themselves. The short version for this piece is that a structured hire followed by a three-month probation with real reviews gives you two working checkpoints before rights attach, where the old template gave you one, held too late to use.

If an offer letter is going out this month

If an offer letter with a six-month probation clause is going out this month and nobody has checked what January does to it, a short message gets you a direct read on whether the wording and the review dates survive the new regime, and what to change if they do not. It comes back from Nick or the team directly, usually the same day, not a call centre and not a templated reply.

Questions employers are asking

Can we still use a six-month probation period after January 2027?

You can, because probation length remains a contractual matter with no statutory limit. What you cannot do is rely on it. Unfair dismissal protection attaches at six months' service whatever the contract says, and the statutory notice week pulls the safe decision point back to around month five. A six-month probation with the decision at the end offers the appearance of a process while providing none of its protection.

Can an employer extend a probation period in the UK?

Only where the contract allows it or the employee agrees, and only before the original period expires. The extension should be confirmed in writing with a new end date, the reason, and what needs to change. It has no effect on when unfair dismissal rights attach.

Does the six-month rule apply to people we hired before the change?

Yes. The trigger is the effective date of termination, so anyone with six months' service when the rule commences on 1 January 2027 is protected from that date, whenever they joined.