Dave Ramsey, the longtime host of a financial advice radio show, recommends that individuals keep three to six months’ worth of expenses as an emergency fund in a checking or money market account that has a debit card or check-writing privileges so you can quickly and easily pay for an emergency expense.
Ideally, your emergency fund would at least be earning 2% to 3% per year to keep pace with inflation, but when even savings accounts are barely paying any interest, this is a difficult task. Some leading online banks, such as Synchrony, offer money market accounts that come with a debit card and/or check-writing privileges (online accounts typically pay more interest than brick-and-mortar accounts). You can search for the best savings account rates by referring to this article.
Consider a certificate of deposit to earn potentially even more interest. The problem with keeping an emergency fund in a CD is that you must pay a penalty to cash out a CD before it matures, although some banks offer no-penalty CDs that let you withdraw your money without sacrificing any of the interest you've earned. Creating a CD ladder, where you buy several smaller CDs that mature at different intervals instead of one large CD, can help you avoid or minimize early withdrawal penalties.
For more information on where to put your emergency fund, read this article.