We live in the gig economy, so many folks are self-employed. For independent contractors, business owners, consultants, and the like, keeping track of money is more complicated. If you make more than $400 in a year, you owe taxes. Nobody will be withholding them from your pay, so you need make quarterly tax payments to the Internal Revenue Service (IRS) and maybe your state tax department. You’re effectively running a business, which means you’ll need to keep a record of money coming in and expenses going out. With receipts to prove it.