Any employee who has at least one year’s service with an employer is entitled to take up to 18 weeks’ unpaid parental leave per child for the purpose of caring for that child. Parental leave may be taken until the child’s 18th birthday.
The parent must have parental responsibility for the child, and must give you 21 days’ notice, stating the dates the parental leave will begin and end.
The entitlement to unpaid leave is a total entitlement to leave, not an annual entitlement, and is therefore calculated by reference to all employment with all employers. So when you are taking on new employees, it is advisable to check with their previous employers as to how much parental leave, if any, they have taken.
Parental leave may be taken in blocks or multiples of a week, up to a maximum of four weeks per year, per child.
Read more about parental leave on the GOV.UK website.
If in doubt, take legal advice.