How do I reverse a working time opt-out?

You simply write to your employer. We suggest the following text:

"Dear employer

I wish to withdraw my opt-out from the working time limit set by the Working Time Regulations as I no longer wish to work more than 48 hours on average each week.

I would ask you to acknowledge this in writing and to let me know when this will come into effect. I look forward to discussing how my hours will be adjusted to take account of this.

Yours sincerely"