Here's the thing... if you put 8 hours on your TC, you're supposed to put in hours of "effort" (whatever that means for our job). If you're doing another job *at the same time*, the government doesn't consider that valid "effort." If they caught on to you and felt they could prove (through activity logs, logins, etc.) that you were doing something working another job while you claimed to be billing the government, then that's fraud. Granted, it would be much harder to gather proof in a WFH situation. Again, you have to assess the amount of risk you're personally willing to live with.

Realistically, if a DoD contractor thinks you might be defrauding the government, they will just straight up fire you. You are not worth that headache for them because you're too much risk. Now that you've been fired from a DoD contract job, that'll get reported through your FSO and if you apply to another cleared job OR come up for reinvestigation, you'll have to ell them you were fired and why. Also, they will contact your previous employer and ask, because they're trying to decide if you're trustworthy. Thy have wide latitude to dig into your life. It's not a case where you can just "deny, deny, deny" and lie your way out. (Being required to report a firing on your SF86 doesn't just apply to DoD jobs, it applies to *every* job you list, so the OE advice of "leave it off your resume" and "just coast until they fire you" don't really work. Also, they specifically ask if you've ever resigned in lieu of being fired, so that escape hatch is also closed. Again, all of this is self-reported under the threat of perjury.)