1 annual. As this is the second Iron Man annual with a new #1 numbering, it is considered Iron Man Annual (3rd series) #1.
Iron Man (2nd series) had no annuals. Iron Man (3rd series) had annuals but they did not start over with a new numbering. Iron Man (4th series) had an annual with #1, but it was explicitly stated as Iron Man, Director of SHIELD #1. Iron Man (5th series) had one annual, which was Iron Man Annual (2nd series) #1.
