You don't necessarily have to be a government employee to qualify for govt rates. In most cases, government contractors also qualify. Some properties will specifically exclude contractors from govt rate elegibility. My company does a lot of govt contract work, so I have a special ID card that states that I am elegible for govt rates. I use this often when the govt rates are the lowest available.

I have been "carded" more often than what others have posted, though. I think it makes a difference where you are staying. For example, when I stay in NYC, I probably get carded 75% of the time. I think this is because the govt rates are usually way below the standard rates there, and so there is more incentive for people to try to abuse it.

I have also used govt rates at properties that specifically exclude contractors, but have never had a problem, even when they card me.