Generally, if you earn interest income on an account that you can use or withdraw from at any time without paying a penalty, then the interest income is taxable. You would need to include the interest income on your tax return.
Go to this section in Credit Karma Tax: 1099-INT Income
If the total amount of taxable interest income you received during the tax year is more than $1,500 then you must complete Form 1040, Schedule B.
For examples from the IRS of taxable interest and nontaxable or excludable interest, see here.