Salary question for $8500 Home Buyer Credit 2009?

Im single. The $8500 Home Buyer tax credit is available to singles with salaries up to $75000. I make more. I know i can recoup half with my present salary but my question is this: Is this based on the Adjusted Gross salary (after deductions)? In other words, if I have a salary of $85000 but $10000 in deductions does this get me the full $8500? Thanks in advance for your answer.