Americans hate filing tax returns, but they love getting refunds. More than three in four taxpayers get refunds, and the average amount they get back is close to $3,000, according to IRS data. That means that for many Americans, their annual refund is the biggest single check they’ll get all year.

But if you’re among the millions expecting a payout from the IRS this spring, make no mistake: That money was yours all along. Getting a refund means you paid too much in taxes last year and the government is paying that money back — without interest. People who underpay, on the other hand, owe interest and possibly a fine as well.

Our handy refund calculator shows you how much you gave up by lending your money to the government interest-free. Play around with it and you’ll see that the answer depends heavily on what you would have done with that money if you’d had access to it over the past year.

Suppose, for example, that you’d put the money in a savings account instead. Interest rates right now are low — really low. If your refund is $3,000, the interest you could have accrued might have been enough to buy yourself a small cup of coffee. But suppose you’d invested the money instead. Last year was a good one for the stock market. If over the course of the year you’d put $3,000 in a basic index fund that tracks the S&P 500, it’d be worth an extra $235 or so today. That’s a solid month’s worth of weekday lunches. Of course, there’s no guarantee the market will repeat those results this year, and investing runs the risk that you’ll lose your refund altogether.

There’s another option with no such risk: paying down debt. Nearly 40 percent of American households carry a credit card balance, and those loans carry high interest rates — more than 13 percent per year on average, according to the latest data from the Federal Reserve. According to a recent survey by Bankrate.com, about a third of taxpayers plan to use their refunds to pay down debt. But they’d be better off paying down that debt over the course of the year. If instead of getting a $3,000 refund come April, you’d been able to pay off $250 in credit card debt each month (or put $250 a month less on your card), you would have avoided more than $300 in interest expenses by Tax Day.

Most Americans don’t seem to have much problem with lending their money to the Treasury interest-free. The Bankrate survey found that 57 percent of respondents wanted to receive a refund, versus 27 percent who hoped to neither owe money nor get any back.

That isn’t too surprising. Getting a government check in the mail (or direct-deposited into your bank account) feels like a windfall. For many people, their annual refund amounts to a savings plan: A third of respondents in the Bankrate survey said they planned to save or invest their refunds. Only 3 percent planned to splurge on a big purchase. There’s some research to support tax refunds as a way of encouraging saving: Economists have found that people are more likely to spend $500 if it shows up as an extra $20 in every paycheck than if it arrives as one lump sum.

Still, as a savings plan goes, waiting for a big tax refund leaves a lot to be desired. It’s pretty much the only way to save that pays no interest, has no chance of a bigger financial gain and doesn’t give you any access to the money if you need it before next tax season.

To be clear, taxpayers shouldn’t necessarily be trying to get their refunds down to zero. If you’re getting back a few hundred dollars, it may not be worth the hassle of rejiggering your withholdings for a few dollars’ worth of interest. And low-income families that qualify for the Earned Income Tax Credit effectively have to get a big tax refund.

But if you don’t qualify for the EITC and you’re consistently getting tax refunds in the four figures, it might be time to take a look at that W-4 form that’s sitting in a file somewhere in your company’s human resources department.

Methodology

Our refund calculator is intended as a rough estimate and is based on a number of assumptions, which may be more or less accurate depending on your exact situation.

All three calculations assume that your overpayment was spread equally across the year. So, for example, a $3,000 refund translates into a $250 monthly overpayment. These calculations also assume you wait until the April 15 filing deadline to get your tax refund — if you file earlier, you’re giving up less interest.

The savings account calculation is based on an interest rate of 0.06 percent (annual percentage yield), the average for accounts insured by the Federal Deposit Insurance Corporation.

The credit card calculation assumes an interest rate (annual percentage rate) of 13.19 percent, the average rate on credit card accounts assessed interest in 2014, according to the Federal Reserve.

The investment calculation is based on the monthly average price of the S&P 500 index. The return doesn’t factor in taxes or fees. (Taxes would generally only be assessed when the shares are sold.)