What pro rata means
Pro rata is Latin for "in proportion." A pro-rata salary is the share of a full-time salary you earn for working fewer hours. It keeps the hourly rate the same and simply scales the pay to your hours.
pro-rata salary = full-time salary x (your hours / full-time hours)For a £35,000 full-time role at 37.5 hours a week, working 22.5 hours (60%) pays £21,000. A job advert that says "£35,000 pro rata" means the full-timer's figure; your actual pay depends on your hours.
Pro rata and holiday
In the UK, part-time workers get the same statutory holiday entitlement on a pro-rata basis, 5.6 weeks of your usual working week. Benefits like pension contributions are typically based on your actual (pro-rata) salary, not the full-time figure.
Tax is separate
This shows gross pro-rata pay. Income tax and National Insurance are then applied to that figure, and because the UK personal allowance is fixed, part-time workers often pay a smaller share of their pay in tax than full-timers on the same hourly rate.