People tend to want to increase their exemptions with their employer if they are continuously paying too much each week in income taxes, and are receiving a large refund at the end of the year. These people may want to invest the money for that year, and earn more income on it, rather than overpay the U.S. government during the year, and earn no interest on that amount. If you earn more than $75,000 per year as a single filer, you must file and pay taxes quarterly.