Due to rounding in the conversion of payroll data into hourly wage rates in the Annual Survey of Hours and Earnings (ASHE) it is likely that a sizeable number of employees earning the NMW are reported in the survey to have a wage rate just above or below this level. This may mean that the estimated number of employees earning exactly at the NMW rate differs from the actual number. In addition, small sample sizes in ASHE for 16 to 17 and 18 to 21-year-olds means the number of job-holders earning a specific wage rate cannot be inferred with sufficient certainty. For these reasons BIS has provided estimates for the number of employees earning a wage at or below the NMW in the UK rather than those paid exactly at the NMW.
This analysis of the 2009 ASHE indicates that 788,000 employees earned a wage at or below the national minimum wage (NMW) rate in April 2009. The corresponding figure from analysis of the 2008 ASHE is 834,000 employees.
The estimates include the number of jobs paid below the NMW. These cannot be taken as estimates of underpayment as there are legitimate exemptions in the legislation including some apprentices and those receiving accommodation from their employer.
Data for earnings is not available at the constituency level because of small sample sizes at this level in the Annual Survey of Hours and Earnings (ASHE).
BIS analysis of the most recent ASHE indicates that a total of 291,000 employees in the Yorkshire and Humber region aged between 16 and 24 years earned a wage rate at or above the level of the National Minimum Wage (NMW) in April 2009.