Guide
Probation periods: a day-one particular with conditions
Updated
Probationary periods are the clause employers are most confident about and most often draft incompletely, because the statutory requirement is not just the length. It is the length and the conditions, on day one, in the same document as everything else.
What the law asks for
gov.uk lists among the principal statement items "how long any probation period is and what its conditions are", and section 1(4) of the Employment Rights Act 1996 requires any probationary period, including any conditions and its duration.
Conditions is doing the work in that sentence. What is being assessed, what notice applies during the period, whether it can be extended and on what basis, and which contractual benefits are withheld until it is passed are all conditions of the probationary period, and all belong in the day-one document.
The two clauses whose absence matters
A shorter notice period during probation. If it is not written, it does not exist, and the contractual notice applies from day one. Employers who believe they can end a probationary employment on a week's notice are frequently reading a policy that never made it into the contract.
An express power to extend. Without one, extending probation is a variation of contract, which requires agreement. An employee who does not agree stays on the original terms and the extension does not happen, which is not usually the conversation anybody wanted to have at that point.
What probation does not do
It does not switch off statutory rights. Discrimination protection, whistleblowing protection, the right to be accompanied and the automatically unfair dismissal grounds all apply from day one regardless of probation.
It does not change the notice a statutory minimum requires once that minimum bites. And it does not make a dismissal fair by itself: probation describes the assessment period, not the standard applied to the decision.
The change to check before you rely on it
Much probation practice rests on the assumption that unfair dismissal protection needs a period of continuous service. The Employment Rights Act 2025 carries a section headed "Right not to be unfairly dismissed: qualifying period and compensation", which addresses exactly that assumption.
Whether and when it applies is a commencement question, and it is checkable on the Act's own page. What is not a good idea is designing a probation policy today around a qualifying period without looking. The whole value of a probationary period to an employer depends on that answer.