The credit union is not required to send a form if the amount is less than $10. You, however are required to report all income, no matter how small, and regardless of whether you got a form or not.
The IRS allows rounding, so an amount of 49 cents or less rounds to 0 and is not reportable. An amount of more than 49 cents is reportable and taxable.
You can find the amount of interest that your credit union paid on your year end statement. You can report that as if you got a 1099-INT (although credit unions call it a dividend, it is actually interest). Just put the credit union name as the payer and put the interest in Box 1.
