What is the correft way to put pa (per annum) after a numerical figure?

eg $1000 pa? $1000pa? $1,000 p.a. ?
Hi Guest,

Welcome to EF.

Your third one (with or without the comma) is correct. The abbreviation for 'per annum' is 'p.a.', and a space should be left after the last digit of the figure. Of course, where there is plenty of room, writing the phrase out would be preferable.
British magazine & advertising usage now seems to favour your first option, 'pa', especially in the context of recruitment.