If you are an employee, your contract of employment should specify your entitlement to annual holidays. This can only be the same or better than the legal minimum that we explain in the rest of this answer.
The law gives all workers, including part time workers, a minimum entitlement of 5.6 weeks from April 1 2009. This builds up from your first day of employment.
You can work out how many days off you should get by multiplying the number of days you work each week by 5.6.
So workers who are contracted to work 5 days a week must get at least 28 days off a year (5 x 5.6) including public holidays.
If you are contracted to work 3 days a week then your leave entitlement will be 16.8 days off a year (3 x 5.6).
A small number of workers are still contracted to work 7 days per week. This is illegal. European rules say that workers must have at least a full day of rest a week (though they can be taken as 2 days off every fortnight).
Working out the leave entitlement is a very simple calculation for those whose leave year starts on April 1. If the new rules come into force during your leave year, you will still get a boost to your minimum entitlement.
Your extra leave will depend on how much of your leave year falls after the change date. If you have an October to October leave year, for example, half your leave year falls after April 1 and therefore you will get half of your full extra entitlement. For a 5-day-a-week worker this would be an extra 2 days.
Those whose leave year starts on 1 January will get three-quarters of the extra entitlement in the leave year that ends on 31 December 2009.
There are no rules on how employers should deal with part days, so they could insist that a worker takes say 0.73 of a days leave. However, the TUC's strong advice is that it would be more sensible for employer simply to round-up entitlements to the nearest half-day. A cost of the small extra increase in entitlements is likely to be outweighed by the benefit of having a simple system that is easy to understand and to monitor.
Many people have contractual entitlements that are much better than the statutory minimum. The average GB full-time worker gets 25 days leave plus 8 bank holidays. Trade union members tend to do better than those who aren't members. Comparing like for like across occupations industries and public and private sectors the average union member gets 2 days more leave than comparable non-members.