Tax Year Prior to 2020: How do I fill out the 1099-int section if I never got one from my bank?

Below a certain interest level (it might be $5; I'm not sure), the bank doesn't need to send a 1099. You can go to your bank statements and add up the interest you got this year and use that number.

Below $10, the financial institution is not required to provide a 1099-INT statement.