They signed a stipulation to leave on certain date or they pay the court fee but they never returned the key nor left on that certain date.

Like charge them as per the lease that stipulates they need to get insurance.

CA's legal interest rate charge is 10%, but there are stipulations around when you can charge that.

If they are not tenants I don't see how this would fall under that stipulation.  

The ones I manage myself from out of state, the tenants know before they sign the lease and the lease stipulates that they agree to schedule access for repairmen in a timely manner.  

There should be a special stipulation along the lines of "All parties agree that tenant will provide time within 3 days of binding agreement for buyer and licensed inspector to access the inside of the property."

However, you should also stipulate in whatever operating agreement that you draw up that there is no recourse.

They don't then turn around and stipulate that you won't get the savings until you're 45.

(Or stipulating that only a government agency can thus check a persons credit without 'misusing' the person's unique identification number?!)

So now we have to stipulate an explicit dollar amount of income, not "3x rent and rent is $1200" - but rather "income must be $3600 minimum".