Annual Leave in Your First Year of Employment (UK)

In your first year of employment in the UK, you build up annual leave at one-twelfth of your annual entitlement on the first day of each month, and you can only take what has built up so far. The right to holiday starts on day one — there is no qualifying period — but the ability to use it is rationed month by month.

That monthly accrual rule is regulation 15A of the Working Time Regulations 1998, and it is still in force in 2026 for workers on regular hours. What changed in 2024 was the position for irregular hours and part-year workers, who now accrue on a completely different basis. This guide separates the two, and untangles the pro-rating question that gets confused with both.

Key Takeaways

• Statutory leave is a day-one right. Regulation 15A limits when you can take it, not whether you have it.
• Accrual is 1/12 of the annual entitlement on the first day of each month of your first year.
• Part-days round up: less than half a day becomes half a day, more than half a day becomes a whole day.
• Irregular hours and part-year workers accrue at 12.07% of hours worked in each pay period instead, for leave years starting on or after 1 April 2024.

The Two Calculations People Confuse

New starters and their managers routinely mix up two different sums. Get them apart and everything else follows.

	Pro-rating	Regulation 15A accrual
Question it answers	How much leave do I get this leave year?	How much can I take right now?
Basis	Proportion of the leave year remaining when you joined	1/12 of the annual entitlement per month elapsed
Applies	Every part leave year, including the first	First year of employment only
Source	Working Time Regulations, regs 13 and 13A	Working Time Regulations, reg 15A

You almost always need both. Pro-rating sets the size of your pot for the part-year; regulation 15A meters how fast you can draw from it.

How Monthly Accrual Works Under Regulation 15A

Regulation 15A(1) says that during the first year of employment, the leave a worker may take “is limited to the amount which is deemed to have accrued”, less anything already taken. Regulation 15A(2A) sets the rate: one-twelfth of the combined regulation 13 and 13A entitlement, credited on the first day of each month.

Two mechanics matter.

It credits on the first of the month, not by the day. You do not accrue a fraction each morning. On the first day of month two you gain another twelfth in one step. Someone who starts on 2 March gains their second twelfth on 1 April, four weeks later — and their third on 1 May.

Fractions round up. Regulation 15A(3) says a fraction other than a half-day “shall be treated as a half-day if it is less than a half-day and as a whole day if it is more than a half-day”. So 2.3 days becomes 2.5, and 2.7 becomes 3. The rounding always favours the worker, and applies at each point you check the balance — not just at the end.

Monthly accrual table (28-day full entitlement)

One-twelfth of 28 days is 2.333 days per month.

Month of employment	Raw accrual	After reg 15A(3) rounding
1	2.33	2.5 days
2	4.67	5 days
3	7.00	7 days
4	9.33	9.5 days
5	11.67	12 days
6	14.00	14 days
7	16.33	16.5 days
8	18.67	19 days
9	21.00	21 days
10	23.33	23.5 days
11	25.67	26 days
12	28.00	28 days

This table is the answer to “can I book two weeks in month four?” — you would have 9.5 days available, so the answer is no unless your employer allows leave in advance of accrual, which many do as a matter of policy.

Worked Example: A Mid-Year Starter

Aisha joins on 1 May. Her employer’s leave year runs 1 January to 31 December. She works five days a week, and the company gives the statutory minimum of 28 days including bank holidays.

Step 1 — pro-rate her entitlement for this leave year. Eight months of the leave year remain out of twelve. 28 × (8 ÷ 12) = 18.67 days, which her employer rounds to 19.

Step 2 — apply regulation 15A to see what she can take when. Her accrual runs against her annual entitlement of 28, credited monthly from her start date.

• 1 May (month 1): 2.33 → 2.5 days available
• 1 July (month 3): 7 → 7 days available
• 1 September (month 5): 11.67 → 12 days available
• 1 December (month 8): 18.67 → 19 days available

Step 3 — the two numbers meet at year end. Her pro-rated pot for the leave year is 19 days, and by December she has accrued the right to take all of it. From 1 January her second leave year starts, regulation 15A no longer applies, and she has the full 28 days available from day one.

The practical lesson: Aisha can book her summer holiday, but not a three-week trip in June.

Irregular Hours and Part-Year Workers Are Different Now

For leave years beginning on or after 1 April 2024, irregular hours and part-year workers accrue statutory leave at 12.07% of the hours actually worked in each pay period, under the reforms introduced by the Employment Rights (Amendment, Revocation and Transitional Provision) Regulations 2023. GOV.UK’s reform guidance defines an irregular hours worker as one whose paid hours in each pay period are “wholly or mostly variable”, and a part-year worker as one required to work only part of the year with unpaid gaps of at least a week.

For those workers the monthly-twelfths mechanic is beside the point. Their entitlement is an hours figure that grows with every shift, in the first year and every year after, and their employer may also pay rolled-up holiday pay at 12.07% of total pay if it is shown separately on the payslip. Our guide to variable-hours holiday entitlement after Harpur Trust v Brazel covers how this replaced the old case-law position.

Can Your Employer Let You Take Leave Before You Have Accrued It?

Yes. Regulation 15A is a floor on what the worker can insist on, not a ceiling on what the employer may allow. Plenty of employers front-load the full pro-rated entitlement from day one because it is simpler to administer and better for recruitment.

If yours does, check one thing: whether your contract lets the employer recover overtaken leave from your final pay if you leave early. That deduction is only lawful where it has been agreed in writing beforehand — see unused annual leave when you quit.

What This Means for You

If you are a new starter, ask HR for two figures in writing: your pro-rated entitlement for this leave year, and whether the company applies regulation 15A accrual or front-loads the balance. Those two answers tell you everything about what you can book and when. Do not assume bank holidays are on top — in the UK they usually come out of the 5.6 weeks.

If you are an employer, two failure modes are common and both are avoidable: forgetting to round up under regulation 15A(3), which quietly shortchanges every new starter by up to half a day at a time, and running first-year accrual on a spreadsheet that credits daily rather than monthly. Decide your policy once — statutory accrual or front-loaded — write it into the offer letter, and apply it identically to everyone.

Leave Balance applies first-year accrual and pro-rating automatically from each employee’s start date, with the statutory rounding built in, so a new starter’s available balance is always correct on the day they ask. Flat $10/month, unlimited employees, 14-day free trial.

This article is general information about UK employment law, not legal advice. Check your own contract, and take advice on your specific circumstances.