- Gas and car insurance. Unfortunately, gas is creeping very close to $4 a gallon in the U.S. for the forseeable future. Car insurance, luckily, can be paid monthly in small amounts, or in advance for a discount. Remember, if your car gets towed because you don't have insurance, you're homeless and on the streets.
- Laundromats. If you can find a friend or family member who is willing to let you do your laundry for free, you'll save the $5-$10 weekly cost of trying to keep things clean. Try to purchase laundry supplies from dollar stores, or buy them on sale in stores rather than at the laundromat, where the cost is excessive.
- Medical bills or vet bills. Of course anyone can go to the emergency room for something dire, but if you are diabetic or have another chronic condition, medical expenses can eat you alive. Many cities have free clinics where medical needs can be addressed for free or nearly free. The catch is, you have to wait for the scheduled day they serve the public, or make an appointment, prolonging the time until your medical problem can be addressed. If your state has public health insurance, see if you can enroll prior to becoming homeless. Many of them have very long waiting lists, so the sooner you apply, the better.
- Equipment. This includes items like heaters in the winter, and solar fans in the summer. Or a decent sleeping bag.
- Unforeseen expenses. This is a huge category, that can include car repairs, money for a motel room during extreme weather, or police tickets for speeding, parking or vagrancy.
You'll have enough planned expenses to have to pay for (gym membership, storage), let alone have to scrape up the cash to handle emergencies. Thinking ahead helps a lot, but luck, unfortunately, which you can't control, will also play a major role.