As of 13 August 2026, AI can only partly calculate a new employee's UK holiday entitlement.

What to actually do

1. Hand it to a person

   The route this page recommends

   A person who owns the outcome does this end to end, worth it when the failure is dear.

2. Use a tool built for this

   Second choice

3. Do it yourself

   The distant third

   A chat interface, chat-fluent skill, and roughly 30 minutes until you can act on the result.

   How to actually do it

   1. Open the employee's contract, offer letter and your organisation's leave policy, then gather the start date, leave-year dates, working pattern, contracted leave allowance and bank-holiday treatment.
   2. Check whether the employee works fixed days, fixed hours, shifts or irregular hours, and record the pattern exactly rather than describing it as full-time or part-time only.
   3. Paste the gathered details into the prompt, replacing every bracketed slot and writing "unknown" where the contract or policy does not say.
   4. Ask the model to calculate statutory entitlement and show its assumptions, then save the result with the employee's onboarding or payroll record.
   5. Open the relevant GOV.UK holiday entitlement guidance and compare its rule for this working pattern and part-year period with the model's calculation.
   6. Ask an HR or payroll colleague to confirm the leave-year dates, contractual allowance, bank-holiday treatment, carry-over rules and any irregular-hours calculation before recording the figure.
   7. Send the confirmed entitlement to the employee through the normal HR or payroll process, including whether bank holidays are deducted from the allowance.

   Prompt

   Calculate a new employee's UK statutory holiday entitlement, but do not present the result as confirmed until the assumptions have been checked. Use current GOV.UK rules only and say when a rule may have changed or needs HR confirmation.
   
   Employee details:
   - Employment start date: [DD/MM/YYYY]
   - Employment end date, if fixed-term: [date or not fixed-term]
   - Leave year start and end: [dates]
   - Working pattern: [for example, five fixed days per week, three fixed days per week, shifts, or irregular hours]
   - Hours per week and working days: [details]
   - Expected number of weeks worked in the leave year: [number, if relevant]
   - Contractual annual leave allowance: [number of days or hours, if known]
   - Whether bank holidays are included in that allowance: [yes, no or unknown]
   - Any carried-over leave: [details or none]
   - Any other relevant contractual term: [details or none]
   
   Show:
   1. The statutory entitlement in days or hours, stating which unit is appropriate.
   2. The calculation step by step, including any part-year or start-date adjustment.
   3. The assumptions and missing facts that could change the result.
   4. Whether the contractual allowance is more generous than the statutory minimum.
   5. A short list of what HR or payroll must confirm before recording the entitlement.
   
   Do not invent missing facts, do not give legal conclusions, and do not calculate holiday pay unless I separately provide the necessary pay information. Link each rule to the relevant GOV.UK page where possible. State clearly that this is not professional advice.

   Open it prefilled in ChatGPT or Claude, or copy it into Gemini, which takes no prefill link.