An unlawful deduction from wages happens when your employer takes money out of your pay without a proper legal basis, whether that’s the law itself, your contract, or your prior written consent. If none of those apply, you’re entitled to claim the money back.
In practice
A removals company deducting fuel costs from a driver's pay with no contractual basis for doing so was an unlawful deduction from wagesAn unlawful deduction from wages happens when your employer takes money out of your pay without a proper legal basis, whether that's the law itself, your contract, or your prior written consent. If no..., and the tribunal ordered it repaid.
See also
Legislation covered