How to work out when an employee reaches six months of service

Last checked 17 Oct 2026. Great Britain only. Dates can change.

Add six calendar months to each employee's start date. If that month has no matching day, use the last day of the month. Then check the result against the effective date of termination (EDT), because from 1 January 2027 the EDT decides which unfair dismissal rules apply.

How long this takes

About ten minutes for a team of 20 once you have the start dates in one list. A larger workforce takes longer, mostly to clean the data and chase gaps in service.

Why the effective date of termination matters

GOV.UK lists the move from a two year to a six month qualifying period for unfair dismissal for January 2027, and the regulations (SI 2026/559) bring it in on 1 January 2027. Regulation 4 keys the transition to the EDT:

• If the EDT is on or after 1 January 2027, the new rules apply, even if the dismissal or notice came earlier.
• If the EDT is before 1 January 2027, they do not.

The EDT is usually the day notice ends, or the day a dismissal without notice takes effect (section 97 of the Employment Rights Act 1996). For the length of service test, section 97 can also move the EDT later by the statutory minimum notice, even where you pay in lieu. GOV.UK gives that minimum as seven days for someone with between one month and two years of service. So do not rely on the date you tell the person. Work out the EDT for each case. See unfair dismissal from 1 January 2027.

Steps for one employee

1. Find the date they started work. Section 211 says continuous employment begins with the day the employee starts work. That is not necessarily the offer date or the date the contract was signed.
2. Check for earlier service that may count, such as a transfer from another employer or an earlier stint with you (see gaps below).
3. Add six calendar months to that start date.
4. If the month you land in is shorter, use its last day. A 31 August start gives 28 February, not 31 February.
5. Subtract one day. Six months of service is complete at the end of the day before that date, because the start day counts as day one. Diary the earlier date: it is the cautious choice for an employer. We have applied the usual corresponding-date approach, so if a decision falls within a few days of the line, take advice.
6. For anyone who may leave, write down the EDT and how you worked it out.

Steps for a whole workforce list

1. Export a list with a staff ID and a start date for every employee (not agency workers or contractors without checking their status first).
2. Add a column for any adjusted start date where earlier service counts.
3. Add a column that adds six months to the adjusted date and takes off one day, which gives the day the six months is complete. In a spreadsheet, EDATE does the adding and handles short months for you.
4. Add a column for the date two years after the start, so you can see who already has two years.
5. Sort by the six month date and mark three groups: already past two years, six months reached by 1 January 2027, and later.
6. Diary a reminder four weeks before each six month date, so any probation review happens first.
7. Re-run the list whenever someone joins, leaves or has their start date corrected.

Worked example

All four people below are fictional.

• Amara started on 1 July 2026. Six months on is 1 January 2027, so her six months is complete at the end of 31 December 2026. She has six months of service on the day the new qualifying period begins.
• Ben started on 31 August 2026. There is no 31 February, so six months on is 28 February 2027 and his six months is complete at the end of 27 February 2027.
• Chidi started on 14 October 2026. Six months on is 14 April 2027, so his six months is complete at the end of 13 April 2027.
• Dani starts on 15 December 2026. Six months on is 15 June 2027, so her six months is complete at the end of 14 June 2027.

Now take Amara. A manager gives her one week's notice on 28 December 2026, so notice ends on 4 January 2027. The EDT is 4 January 2027, which is after 1 January 2027, so the new rules apply to her. Had notice ended on 29 December 2026, the EDT would fall before 1 January 2027 and the old two year rule would apply. The exception is where she was given less than the statutory minimum notice, or was paid in lieu, because section 97(2) can then treat the EDT as the day statutory notice would have ended. This example shows how the dates work. It is not a suggestion about timing any dismissal. Other protections apply from day one, including those on discrimination and whistleblowing.

Gaps in service

Some absences do not break continuous employment. GOV.UK lists sickness, maternity, paternity, parental and adoption leave, annual leave and temporary lay-offs, among others. Strike days are not counted towards the total but do not end the period. Section 211 also deals with periods that do not count but do not break continuity.

For anything else, such as someone who left and came back, moved from agency work to a direct contract, or joined through a business transfer, do not guess. Check GOV.UK's guidance on continuous employment or ask Acas, and record the outcome.

What to record

• Staff ID and actual start date
• Any adjusted start date, and the reason
• The six month date and how you calculated it
• Who checked it, and the date
• For any exit: the date notice was given, the notice period and the EDT

Common mistakes

• Using the contract signing date instead of the start date.
• Adding 180 days instead of six calendar months.
• Forgetting that month end start dates clamp to a shorter month.
• Using the date you tell someone they are dismissed instead of the EDT.
• Assuming a gap always resets the clock, or never does.

This guide is general information to help you prepare, not legal advice.

More guides

• How to run probation reviews before 1 January 2027
• How to brief your managers on the Employment Rights Act changes in 20 minutes
• How to keep a dated record of what you do to prevent sexual harassment
• How to work out statutory sick pay under the new rules