IThe current extension of the Greek bailout money expires on June 30th.  If the extension is not granted, Grece will have to rely on tax money to. Operate.   Greece has a lot of trouble collecting taxes.

Also, if the bailout monies are not extended, Grece will be unable to pay ht emoney it owed the IMF.

Although Greece has always had trouble filling the public coffers, they have in the past made their IMF payments.   This would be the first time they have failed to pay.    It might kick off a series of actions leading to their exodus from the euro zone and ultimately the EU .