(I actually have a “stupid mistakes” category in my money system. When I first started this, I saved $20/month for unexpected expenses. Then, within two months, I had to go to the doctor for $600 and I got a traffic ticket for more than $100. That changed things quickly, and I currently save $200/month for unexpected expenses. At the end of the year, if I haven’t spent it, I save half and I spend the other half.)