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How does annual percentage yield (APY) work?

Annual percentage yield is important when choosing a deposit account.
April 19, 2018

By Kathryn Pins

When opening a deposit account, it’s important to know that not every account is the same. You want an account that will be easy to use and will help your money earn more money. The easiest way for you to do this is to earn interest on that account every month. Compound interest is your friend, which is why annual percentage yield or APY is so important.

The official definition of APY is the interest rate (aka “rate of return”) on a deposit account based on a compounding period of one year. The simple definition is that APY is the total amount of interest received when you leave your funds in the account for one year.

How is APY determined?

The APY percent varies depending on the financial product and your financial institution. “Many factors go into our rates, including our current financial position, our competition, and the Federal Reserve rates,” says Dana Vas Nunes, Alliant’s director of deposit products. “We are focused on providing superior rates for our members and our high APY on deposit accounts reflects that.”

The more money you have and the higher the annual percentage yield, the more you will receive in interest.

If you have money in an account, you want it to make money. This philosophy should apply to all of your deposit accounts regardless of liquidity. That said, APY applies to all deposit accounts.  This includes checking, savings, certificates, and money market accounts.

What is the difference between the Interest Rate and APY?

When I first started comparing deposit accounts, I noticed two different interest acronyms listed on some products. The percentages were similar, so it was confusing as to why I saw an APY and the Interest Rate.

In short, for a deposit account, the Interest Rate is the percent return without compounding interest included. It is also known as simple interest. The APY is the total amount of interest received when you leave your funds in the account for one year. APY is the percent return including compound interest after a year.

Think of it this way. You have $20,000 in a savings account for a year. The rate is 1.49 percent. If you do the math ($20,000 x 1.49), you get $20,298.00. However, this number is wrong because it doesn’t take compound interest into account.

At Alliant Credit Union, your savings account is compounded monthly. Therefore, at the end of the year, you actually have $20,300.04 in your savings account. Your account has increased by 1.50 percent in a year. This percent is your APY. Banks use APY to show the actual interest increase if you kept the money in the account for a year.

Why is annual percentage yield important?

Let’s use an example to illustrate why a high APY is important. Say you have $10,000 in a savings account. At 0.08 percent APY, your $10,000 will become $10,008.00 after compounding monthly for a year. In a high-rate savings account at 1.50 percent APY, that $10,000 will become $10,151.05 after compounding monthly for a year. The effect of compound interest on your deposit accounts can be huge beyond 12 months.

When choosing your financial products, open an account that will earn more money on your money.

What is a high rate?

Now that you understand APY better, you probably want to make sure you have a high annual percentage yield.

APY rates are very dependent on the credit union or bank you choose. The average APY for a savings account is almost zero according to the New York Times. However, there are many options that pay more, including Alliant’s High-Rate Savings. This account offers an APY of 1.50 percent with no maximum balance.63

The average checking account APY, according to Bankrate, is also low at .06 percent. Again, Alliant’s High-Rate Checking offers a better rate at 0.65 percent APY.61 (All info is from 4/19/18).

Certificate and CD APYs will depend on the amount you put into your account and the timeline. Certificates typically give you an even better interest rate on your money than in a savings account. However, you can’t withdraw the money for an extended period. Certificate APYs vary, so it’s important to do your research.


Kathryn Pins is a marketing content specialist at Alliant. She’s passionate about finding and communicating meaningful financial information with Money Mentor readers. Kathryn is a saver who gets more excited about certificates and her Roth IRA than shopping. When she does spend her earnings, it’s on furthering her education, travel, unique experiences, and loved ones.