Workers are entitled to 5.6 weeks’ statutory holiday each year = 28 days; 20 days holiday and 8 days of Bank Holidays.
The 28 days of statutory entitlement cannot be carried forward into the next holiday year.
However, if you offer over and above the statutory holiday amount this can be carried forward legally but you need to determine what rules you want to have around this, and ensure they are written into your holiday policy and communicated to all.
For example, you may offer an additional 5 days holiday which could be carried forward into the new leave year but you need to state that this additional leave has to be used by the end of March.