The difference in interest accrual over a presumed 30-day month over a presumed 360-day year or over the actual number of days spread over the 360-day year.
30/360 accrues interest over a presumed 30-day month over a presumed 360-day year.
Actual/360 or 365/360 accrues interest over the actual number of days spread over a presumed 360-day year. The result is a slightly higher actual interest accrual when you use 30/360.
Most of our customers use 30/360