Probation period calculator
Enter the start date and probation length to see when probation ends, when unfair dismissal protection starts, and the last day to give notice if things are not working out.
Why probation dates matter from 2027
Until the end of 2026 an employee needs two years' service to claim ordinary unfair dismissal, so a three- or six-month probation sat well inside that window. From 1 January 2027 the qualifying period is six months. A dismissal that ends employment after six months' service, counting notice, must have a fair reason and follow a fair process, even if the employee is still on probation.
- Probation end: the contractual review point. It has no legal effect on unfair dismissal rights.
- Protection starts: the day six months' service is complete, or 1 January 2027 for anyone who already has six months by then.
- Last day to give notice: notice given on this day ends employment the day before protection starts.
- Last day to pay in lieu: if employment ends with pay in lieu of notice, one week of statutory notice is still added when counting service, so this date is the same as giving one week's notice.
Worked examples
Six-month probation starting 2 November 2026
Probation ends on 1 May 2027, which is also the day six months' service is complete. To end employment before protection starts, one week's notice must be given by 23 April 2027. A final review at the end of month five, or a five-month probation, avoids the clash.
Three-month probation extended by two months
The employee starts on 4 January 2027. Probation ends on 3 April and the extension runs to 3 June. Protection starts on 3 July, so with one week's notice the last day to act is 25 June. The extended probation still ends in time.
Someone who started in May 2026
Six months' service is complete on 17 November 2026, while the two-year rule still applies. Protection under the new rule starts on 1 January 2027, so employment would need to end, counting notice, by 31 December 2026.
Good practice for employers
- Set probation at five months or less, or hold the final decision by the end of month five.
- Hold reviews at regular points, for example after one and three months, and keep short written notes.
- Tell the employee about concerns early and give support and time to improve.
- Check the contract allows an extension before relying on one, and confirm any extension in writing.
- For anyone near or past six months' service, follow a fair procedure and the Acas Code of Practice.
Frequently asked questions
How do I calculate a probation end date?
Count the probation length from the first day of employment. A six-month probation starting on 1 May ends on 31 October. A 12-week probation starting on a Monday ends on the Sunday 12 weeks later.
Is there a legal maximum probation period in the UK?
No. Probation is set by the employment contract. Three to six months is common. From 1 January 2027 the unfair dismissal qualifying period is six months, so a probation of six months or longer runs past the point where employees gain that protection.
Can probation be extended?
Only if the contract or probation policy allows it, or the employee agrees. Extending probation does not delay unfair dismissal rights. Those start after six months' service whatever the probation status.
What happens at six months' service from 2027?
For employment ending on or after 1 January 2027, an employee with six months' continuous service can claim ordinary unfair dismissal. The employer then needs a fair reason, such as capability or conduct, and a fair process.
Why does notice matter?
Service is counted to the date employment ends. If notice is worked, that is the end of the notice period. If the employer pays in lieu of the statutory minimum notice, one week is added to the end date when counting service, under section 97(2) of the Employment Rights Act 1996.
Is anyone protected from day one?
Yes. Dismissal for an automatically unfair reason, such as whistleblowing, pregnancy, health and safety or asserting a statutory right, needs no qualifying service. Discrimination claims also need no service.
Does this apply in Northern Ireland?
No. Northern Ireland has its own employment law. This calculator covers England, Scotland and Wales.
Sources
- Employment Rights Act 1996, section 108 (qualifying period)
- Section 97 (effective date of termination and notice extension)
- Section 86 (statutory minimum notice)
- Employment Rights Act 2025 and its commencement regulations
This calculator gives general guidance based on the Employment Rights Act 1996 as amended by the Employment Rights Act 2025. It does not cover every situation and is not legal advice. For your own case, speak to Acas, a trade union, Citizens Advice or an employment solicitor. Time limits for tribunal claims are short, so act quickly.