In this case, your company will need to account for accrued interest revenue on Dec. 31, 2015, to close out the books for the month and year, well before the note comes due on Feb. 8, 2016. This happens frequently in accrual accounting — revenue is recognized before it is received in cash.
To calculate interest revenue for the 21 days up to the end of the year, you would follow the same steps as in the interest receivable example.
Principal x Interest x Time = Interest revenue
or
$10,000 x 9% x (21 days/360 days) = $52.50