Annuities where the payments occur at the end of each time period are called annuities due, whereas ordinary annuities refer to annuity streams with payments occurring at the beginning of each time period.

Annuities Due

Annuities Due refer to a series of equal payments made at the beginning of consecutive periods over a fixed length of time, often used in finance to represent contracts that require such payments.

Ordinary Annuities

Ordinary annuities are a series of equal payments made at the end of consecutive periods over a fixed length of time.