So I know you didn't post this to get a lecture or advice on this but I'm going to give it anyways because what you are doing drives me nuts!!! At least you don't take your windfall and use it on a big purchase. I will give you credit for that. However, if you are using it to pay down your mortgage or car loan, why not do that earlier. If you pay more every month during the year rather than a one time bigger additional payment at tax time, you will pay off the mortgage or other loan sooner and you will spend less money over the life of the loan. Or, if your work has a defined contribution retirement plan that allows employee contributions, you would be sooooo much better off in the long run putting an extra percentage or two into that every year. Anything but letting the government sit on that money all year! Ughhh!! Edit: Not to belabor the point, but if your mortgage company or car loan company told you that they wanted you to pay X amount of $ every month over and above what you already owe, but that they were not going to apply it to your principal balance until the end of the year, would you do it? That's basically what you are doing by purposely paying the government more than you owe them each month. Paying the mortgage or car payment a couple extra hundred dollars a week is good in theory, but it just doesn't work for me. I know I'd piss some of that money away. Having less take home money each week keeps me on a tighter budget, and I refuse to keep a credit card balance. $10,000 at 3.5% for the year costs me about $200 a year. I'd piss that away easily.