When you have a new starter and you are entering their holidays per year you should enter the total holidays they are entitled to in a normal year and the system will prorate this based on their start date, contract end date, total entitlement and when you have set the start of your holiday year to be.
If you enter the allowance already prorated for that year we will then prorate that again so it will show a lower number.
The option to prorate timeoff for new starters is only available when using a timeoff type that pulls from an individual allowance. This is done through:
Administration > HR > Time off management > Time off types
Editing a time off type using the 'edit' icon will give you the option of whether you would like to prorate timeoff for new starters. However, this option will only appear when 'individual allowance' is selected for the 'Deduct from employee allowance?' field.