IRS sent me a 1099-INT because I made an estimated tax payment that is now older than 1 year. I did not receive a check though, so how do I know the balance with interest

[DMarkM1]

First, you report the interest from the 1099-INT as you would any other interest from a bank, for example, in the "Interest and Dividends" section under the "Income & Expenses" tab.  If you wish to see what your tax account looks like with the IRS, you can order an account transcript here.