[ineedasername]

Where I work they don't allow any, at all. So if you're out, say to take care of a sick relative for a few weeks, you can't make up any time, or get credit for trying to stay up to date. Even if there's something urgent and you end up spending hours in teleconference and then more time working on the issue, you're not allowed to put those hours in to your time sheet as time worked.

[CydeWeys]

This sounds illegal (wage theft). You should inquire with your state's Department of Labor.

Google has a very strict policy of not being allowed to work whatsoever when you are out on unpaid leave, for obvious reasons.