Per Annum

Once per year.
Example: Insurance premiums are paid on a per annum basis.

Percentage Rent

Additional rent paid by a retail Tenant which is based upon a percentage of gross sales in excess of a specified dollar amount (the breakpoint). Also called Overage Rent.
Example: ABC Retail signs a 5-year lease which requires ABC to pay base rent of $50,000 a year plus percentage rent in an amount of 4% of gross sales in excess of $1,250,000. During the third lease year, gross sales of ABC equal $1,400,000. ABC would be required to pay percentage rent of $6,000 (calculated as $1,400,000 - $1,250,000 x 4%).