Ask a small employer what probation is for and most will say: “to see if they work out before they get rights”. From 1 January 2027 that window is six months at most, whatever the contract says.
There is no statutory probation
When the Employment Rights Bill was introduced in October 2024 it would have made unfair dismissal a day-one right, with a lighter-touch “initial period of employment” at the start. That model was dropped. In November 2025 the government announced a six-month qualifying period instead, which it said can only be changed by primary legislation, and that is what section 25 of the Act does.
So probation remains a contractual idea. Acas says there is no legal requirement for a probation period and that it can be any length. The Act did not change that.
What did change: six months
For any dismissal where employment ends on or after 1 January 2027, the employee only needs six months’ continuous service to claim ordinary unfair dismissal. Six months are complete on the day before the six-month anniversary of the start date. For someone starting on Monday 4 January 2027, that is 3 July 2027.
Compare common probation lengths for that start date, with the review 14 days before the end:
| Probation | Ends | Review by | Ends before protection? |
|---|---|---|---|
| 3 months | 3 April 2027 | 19 March 2027 | Yes |
| 12 weeks | 28 March 2027 | 12 March 2027 | Yes |
| 5 months | 3 June 2027 | 20 May 2027 | Yes |
| 6 months | 3 July 2027 | 18 June 2027 | No — ends the day protection starts |
| 9 months | 3 October 2027 | 17 September 2027 | No |
The review dates step back from weekends; with England and Wales bank holidays, a review landing on Good Friday or Easter Monday moves to the Thursday before.
Choosing a length
- Three months suits most roles where you can judge performance quickly: retail, hospitality, admin.
- Four or five months suits roles with a longer learning curve, and still leaves room to extend by a month.
- Six months or longer is lawful, but any decision after six months needs a fair reason and a fair process. Acas notes that ending probation earlier does not avoid legal risk.
Whatever you choose, make sure the contract says how probation can be extended and by how much.
Work out the review date
Hold the probation review by Friday, 16 April 2027
- Probation ends
- 1 May 2027
- Unfair dismissal protection starts
- 1 May 2027
- Overlap
- Probation is still running when protection starts, so any decision after that date is made with full unfair dismissal rights in play. Acas notes that ending probation earlier does not remove legal risk.
To track everyone at once, add start dates in the staff dates tool: it uses your usual probation length, flags anyone whose probation runs past their protection date, and exports the review dates to your calendar.
A review that holds up
A probation review does not need to be elaborate, but it should leave a paper trail:
- Objectives in week one. Three to five things the person needs to show, in plain words.
- A check-in halfway. What is going well, what needs to change, any support offered.
- The formal review before the deadline. In person, with notice of what will be discussed.
- A written outcome. Pass, extend (with the new end date and what needs to improve) or fail, with reasons.
If you fail someone, give at least the contractual notice — and never less than the statutory week once they have worked a month.
Staff already on probation on 1 January 2027
The change applies to people already employed. Anyone who started on or before 2 July 2026 has six months’ service by 1 January 2027 and is protected from that day, whatever their probation status. Some examples:
| Started | Probation (6 months) ends | Protected from |
|---|---|---|
| 1 June 2026 | 30 November 2026 | 1 January 2027 |
| 1 August 2026 | 31 January 2027 | 31 January 2027 |
| 2 November 2026 | 1 May 2027 | 1 May 2027 |
For the June starter, probation has already ended before the rule changes, so nothing changes in practice. For the August and November starters, a six-month probation ends the same day protection starts — the review needs to happen well before.
Extending probation: what to write
If the contract allows extension, an extension letter should say:
- the new end date, and that it falls before (or after) six months’ service, so both sides know where they stand;
- what specifically needs to improve, and how it will be measured;
- what support you will give, such as training or more frequent check-ins;
- when the next review meeting will be.
Extensions of four to eight weeks are common. If an extension takes someone past six months, follow your capability procedure for any later decision, because ordinary unfair dismissal rights will apply.
Mistakes to avoid in 2027
- Extending past six months as a matter of habit. It does not delay protection; it just means your decision comes later.
- Leaving the review to the last week. A Friday review before a bank holiday weekend can slip past the date protection starts.
- Assuming probation means no rights. Discrimination, whistleblowing, pregnancy and asserting statutory rights are protected from day one.
- Treating everyone already employed as “safe”. Anyone who started on or before 2 July 2026 is protected from 1 January 2027.
More on the legal change in unfair dismissal qualifying period changes.