Included within the Terms of the Armistice forced upon France on 22 June 1940 is Article XVIII:
The French-Government will bear the costs of maintenance of German occupation troops on French soil.
For the occupation army of 300,000 men, this was calculated to be 20 million reichmarks. An exchange rate of twenty francs to one reichmark was imposed, resulting in a daily bill of 400 million francs. This has been estimated to be fifty times the true cost of the occupation.
A great deal of agricultural and industrial produce was also demanded from France:
Photos of German officers leaving France when their tour of duty ended show them followed, like explorers, by trains of local bearers carrying their booty. The policy of plunder intensified as the Reich grew increasingly desperate to prop up its own failing economy and its faltering armies on the Eastern Front. France was being slowly bled dry by the outflow not just of meat and drink, fuel and leather, but of wax, frying pans, playing cards, axe handles, perfume and a host of other goods as well.
From Occupation: The Ordeal of France 1940-1944 by Ian Ousby.