When you’ve built up a surplus of cash, it’s hard to feel like you’re doing anything wrong. After all, a surplus is indicative of a frugal lifestyle built on a foundation of spending less than you earn. Who could criticize that?

But money is more than just a resource you need to stock up – it’s a tool that can create even greater wealth if used correctly. In other words, money that’s just sitting around is a wasted opportunity.

There are plenty of things you could be doing with that extra cash that are low-effort and low-risk. If you’re ready to get your money working for you, consider these options.

How Much to Keep on Hand

You’re going to hear varying numbers here, but you should aim to keep six month’s worth of your must have expenses as an emergency fund (think rent, mortgage, utilities, groceries, insurance, and essential items you’ll definitely need to pay for no matter what). That amount will cover you in case you lose your job, face a prolonged illness or have to take time off work to care for an ailing relative. If you work for yourself or have children, you might consider saving a year’s worth of expenses just in case.

Any cash you’ve tucked away for an emergency account should be kept in a high-interest savings account. A savings account is the perfect tool for this because it’s liquid enough that you can access it within a couple days, but not located in the same checking account you use for daily purchases. You can use the same bank you use for your checking account or another if it offers a better rate.

A high-yield savings account will usually earn you around 1% interest a year if you’re lucky. That amount won’t match inflation, but it’s better than a checking account paying nothing.

Why Keep It Elsewhere

You risk losing money when you store excess cash in a checking account or under your mattress. Money’s like a plant – it can only grow if it’s kept in the right environment.

The longer you keep cash somewhere it’s not growing, the more you lose due to inflation. That means if you keep $1,000 in a checking account that’s not earning interest, it’s worth less every year.

Think of your money as an opportunity. The choice of whether to waste or seize that opportunity is entirely up to you.

It’s important to note though, that while you want to maximize the amount of interest you earn on your emergency fund, this is one chunk of money that for your financial planning purposes, isn’t meant to be invested or utilized in any way that could lose your principal balance. This emergency fund is meant to be available in case of emergencies, and last I checked, we don’t know when those will happen. There is an opportunity to earn more growth and income when deploying additional funds into savings accounts for retirement.

Other Savings Goals

Cash you’re saving for things you’ll need in the next three to five years doesn’t need to be kept in a savings account.

One popular option for short-term savings goals is a CD that will mature in a few years. A CD is insured by the bank and has a specific time in which you hold it. Rates will vary based on the bank you choose, how much you can deposit and where you live. You can compare rates online at Bankrate or NerdWallet.

Money market accounts are another option if you won’t need the money for a couple years or more. Some have higher rates than savings accounts and are also backed by the FDIC. Bonds are another option, but rates vary depending on when they mature and how the economy is doing. Your best bet is a CD or money market for short-term goals.

Invest the Rest

Once you’ve allocated money for your emergency fund and short-term savings goals, it’s time to invest any remaining funds for retirement. This money should be deposited in an IRA, 401k or other long-term savings vehicle. These accounts can provide a much greater return because you won’t have to access them anytime soon.

Popular options for retirement savings include index funds or target-date funds, most of which have low fees and decent returns. A financial advisor or planner can help you pick a fund if you‘re unsure which to go with.

Bottom line, if you’re sitting on more than six months worth of expenses in cash, it’s time to get a plan in place for how to allocate the rest in order to ensure your money is being put to work for you.