Possibly. Some agencies will require you to sign an opt-out form to enable you to work more than 48-hours per week and deliver on certain assignments.
Because of the nature of many contracting assignments, the work required to finish a project will run over the 48-hour week. In order to deliver on this, you legally need to sign a ‘Working Time Regulations 1998’ Opt-out form. Often this obligation will be inserted into the contract between your umbrella company and the agency, and will appear on your contract of employment.
The original legislation was created to prevent exploitation of workers, and while you won’t be forced to sign it – and can choose to withdraw your opt-out at any time – you won’t be allowed to work over 48 hours per week if the paperwork is not in place.