Compensable workday? Or replaceable or...

So, I'm looking for an expression that means something like the title says. I mean, what would be the correct expression when I mean that certain workdays, near holidays, for example, aren't really mandatory workdays. That is, one can do some extra work before those days, so that one doesn't need to come to work at those specific days.

I don't know whether 'compensable workday' is correct, I believe it is not what I'm looking for; and 'replaceable workday' strikes just odd to me. How to put this idea as shortly as possible?

Thanks!