Government

As the landowner and titular head of government, you are entitled to a land-use tax, levied on each person in the economy on an annual basis. This tax is set as fraction of a man-year of labor. If you demand more than about 20 percent of the laborer's time, he will probably become angry, especially since many laborers at the low end of the scale only produce about 0.4 man-years of labor equivalent.

The tax is set aside as hard cash, and you can collect it with your ship at any time. Of course, if someone else captures the planet, he may collect your tax for you. Civil unrest may also diminish your tax receipts. Short-lived revolutionary governments almost always manage to spend or otherwise appropriate whatever possessions of the "bloodsucking fascist landowners" they can get their hands on. By the time the riot is over, no one remembers where the money went.