Since Gregor can no longer communicate with his family, he is limited to listening to their conversations to find out what is happening. He was the major breadwinner, and now the family has no source of income. Gregor overhears them talking about their finances, and is happy to hear that they still have some money in the bank, as well as money that he had earned; despite their general ingratitude towards his hard labors, they have not spent all his money, so there is a safety net.
This money, however, was certainly not enough to enable the family to live off the interest; it was enough to maintain them for, perhaps, one or two years, no more.
(Kafka, The Metamorphosis, gutenberg.org)
Since this money is not enough to live on, the family decides to go to work. His sister takes a job in sales and his mother sews clothing and lingerie for a store. His father, who acts as an antagonist because of his harsh temper, goes to work as a bank messenger. Finally, because of their worsening finances, they rent out one of their rooms, and it is after all of these events that Gregor finally succumbs to the infection of the apple lodged in his back. The family then goes on vacation.