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Aggregating the earnings of people doing more than one job with separate employers would be administratively complex for employers. Information on the number of people with more than one employee job who would pay more national insurance contributions (NICs), and the average increase they would pay, under a cumulative annual basis of assessment for employee’s NICs is shown in “Income tax and national insurance alignment: an evidence-based assessment” published in October 2007. It is available at:
Estimates for employers NICs are not available.