Overtime Calculator UK

How Overtime Pay Works in the UK

Overtime refers to any hours you work beyond your normal contracted hours. In the UK, there is no statutory right to enhanced pay for overtime. The only legal requirement is that your average hourly pay, including overtime hours, must not fall below the National Minimum Wage (or National Living Wage if you are 21 or over). Beyond that minimum, overtime rates are entirely a matter between you and your employer, as set out in your employment contract.

Despite there being no legal obligation to pay more for overtime, many employers do offer enhanced rates as an incentive. Common arrangements include time and a half (1.5 times your normal rate) for weekday overtime, double time (2 times) for weekends or bank holidays, and occasionally even higher multiples for unsocial hours in sectors such as healthcare, emergency services, and manufacturing.

Some contracts specify that a certain number of overtime hours are included within your salary, sometimes referred to as “unpaid” or “built-in” overtime. In these cases, you only receive additional pay if you exceed the built-in hours. If your contract states that your salary covers a 40-hour week including up to 2.5 hours of overtime, you would only start earning overtime pay beyond 40 hours. It is important to understand your contractual terms so you can calculate your effective hourly rate accurately.

The Working Time Regulations 1998 cap the average working week at 48 hours, calculated over a rolling 17-week reference period. You can voluntarily opt out of this limit by signing a written agreement, which you can cancel at any time with notice. Even if you have opted out, your employer still has a duty of care to ensure your working hours do not put your health and safety at risk.

Overtime Rates Explained

Overtime rates are expressed as a multiplier of your standard hourly rate. The most widely used multipliers in the UK are as follows:

Flat rate (1.0x): You are paid your normal hourly rate for overtime hours. This is common in salaried roles where overtime is expected but not incentivised. Your total pay increases, but at the same rate as your contracted hours.

Time and a quarter (1.25x): A moderate premium occasionally used for weekday overtime in some industries. If your base rate is £16 per hour, time and a quarter pays £20 per hour for overtime.

Time and a half (1.5x): The most common enhanced overtime rate in the UK. Widely used across retail, hospitality, manufacturing, and the public sector. On a base rate of £16, you would receive £24 per hour of overtime.

Double time (2.0x): Typically reserved for work on bank holidays, Sundays, or overnight shifts. On £16 per hour, double time pays £32 per hour. Some employers offer double time only on specific days and time and a half on others, so your effective overtime rate may vary from week to week.

When using the calculator, set the multiplier to match the rate your employer pays. If your overtime rate varies (for instance, time and a half on weekdays and double time on Sundays), you can run the calculator separately for each rate and add the results together.

Tax on Overtime Pay

Overtime pay is taxed in exactly the same way as your regular salary. It is subject to income tax and National Insurance contributions through PAYE. There is no special tax relief or exemption for overtime earnings in the UK.

In practice, this means that overtime can sometimes feel less rewarding than expected, because it may push some of your earnings into a higher tax band. For example, if your base salary places you close to the £50,270 threshold between basic rate (20%) and higher rate (40%) tax, overtime earnings that cross that line will be taxed at 40% plus the higher rate of National Insurance. The net effect is that you keep a smaller proportion of each additional pound earned.

If your total income including overtime exceeds £100,000, you also begin to lose your personal allowance at a rate of £1 for every £2 above the threshold. This creates an effective marginal rate of 60% between £100,000 and £125,140. For high earners who regularly work overtime, this can significantly reduce the net benefit of extra hours.

National Insurance adds a further layer. Employees pay 8% NI on earnings between £12,570 and £50,270, and 2% on earnings above that. Your employer pays 15% employer NI on all earnings above £5,000. Overtime increases both your and your employer's NI liability, which is another hidden cost to consider.

Example Calculations

The following examples demonstrate how overtime pay adds up at different salary levels and hours, assuming 52 working weeks per year.

£25,000 Salary, 5 Hours OT at 1.5x

On a £25,000 salary with a 37.5-hour week, the base hourly rate is £12.82. At time and a half, the overtime rate is £19.23 per hour. Working 5 hours of overtime each week gives weekly overtime pay of £96.15, which adds up to £5,000 per year. The total annual pay becomes £30,000 — a 20% boost over the base salary. Before tax, this represents a meaningful increase in take-home pay for someone on a modest income.

£35,000 Salary, 8 Hours OT at 1.5x

At £35,000 with 37.5 contracted hours, the base hourly rate is £17.95. The overtime hourly rate at 1.5x is £26.92. Eight hours of overtime per week totals £215.38 per week, or £11,200 per year. Total annual pay rises to £46,200. This amount crosses the higher rate tax threshold, so some of the overtime earnings will be taxed at 40% rather than 20%, reducing the net gain. Nonetheless, the gross increase is substantial at 32% above base salary.

£50,000 Salary, 3 Hours OT at 2.0x

On £50,000 with a 40-hour week, the base hourly rate is £24.04. At double time, the overtime rate jumps to £48.08 per hour. Three hours per week at this rate gives £144.23 per week and £7,500 per year. Total annual pay is £57,500. Because the base salary already sits near the higher rate threshold, almost all of the overtime earnings are taxed at 40%. The net overtime pay after tax and NI is noticeably lower than the gross figure, but the hourly rate is still attractive.

Overtime and the Working Time Regulations

The Working Time Regulations 1998 set out rules that affect how much overtime you can work and the rest breaks you are entitled to. Under the regulations, most workers cannot be required to work more than an average of 48 hours per week, calculated over a 17-week rolling reference period. This means you can work more than 48 hours in some weeks as long as the average stays within the limit.

You can voluntarily opt out of the 48-hour limit by signing a written agreement. The opt-out can be for a specific period or indefinitely, and you can cancel it at any time by giving your employer written notice. The notice period can be up to three months if specified in the opt-out agreement. Even with an opt-out, your employer has a duty to protect your health and safety and must not impose working patterns that put you at risk.

The regulations also require employers to keep records of working hours for employees who have not opted out. You are entitled to a minimum rest break of 20 minutes if your daily working time is more than six hours, a daily rest period of at least 11 consecutive hours between working days, and a weekly rest period of at least 24 uninterrupted hours in each seven-day period (or 48 hours in each fourteen-day period).

Night workers face additional protections. If you regularly work at least three hours during the night period (typically 11pm to 6am), your average working hours must not exceed eight hours in each 24-hour period. Employers must offer free health assessments to night workers and, where possible, transfer night workers to day work if a health professional advises it.

Understanding these regulations is important if you rely on overtime as a regular part of your income. If you are consistently working long hours, it may be worth checking that your employer is meeting its obligations under the regulations and that your health and wellbeing are not being compromised.