If you want to charge extra for weekend or holidays I suggest you charge time and a half for weekends and double time for holidays. Most customers will be comfortable with this structure since it closely matches the familiar work day environment. Will they want to pay it? Probably not, but at least they will understand the basis for the rate! Use these numbers as a starting point for negotiation.
I decided not to quote weekend or holiday rates on any printed materials or on my website. Frankly, I didn’t want to advertise the fact that I might be willing to work outside of the regular Monday through Friday hours. I wanted to keep my weekends for family, rest and fun. If the customer asks, or the job demands it, I’ll tell the customer that there will be a surcharge for weekends or holiday work.
I’ve never been successful in charging overtime rates. In every instance where I might have charged overtime I’ve never felt comfortable doing it. However, if I had an employee and I was paying overtime to them I would definitely pass the cost on to the customer.