Emergency Tax
Emergency tax is a coding used by employers if they do not know an employees tax code.
Employees allocated an emergency tax code will receive a single person's tax allowance and nothing else – ignoring any other tax breaks they may be entitled to. This could result in someone paying too much tax, but should this happen it can be corrected with a refund from the HM Revenue and Customs once a person's correct tax code becomes known and applied.
Employees stop paying emergency tax after the tax office sends a PAYE [pay as you earn] tax code to them and their employer, and the details of employees' previous earnings and tax paid that tax year is known.