How I deal with stupid money mistakes
In Quicken (or whatever budgeting software you use), when you enter an expenditure, you can assign it a category (e.g., gasoline, clothing, cell phone, etc).
I added an extra category to my budget: Stupid Mistakes. This is for things I have to spend money on when I make do something dumb, like getting a library fines, having to switch a flight because I didn’t plan ahead, or paying an extra fee because I don’t have any cash on me.
When I started paying attention to my stupid mistakes, I basically eliminated them altogether within 6 weeks. It’s amazing how a budget–one you created yourself–can change your spending behavior. Now I take the money I would have spent on mistakes and put half into savings and spend half on myself.
How much do you spend on mistakes every month?

