You shouldn't be worried about the FR if your stated income on the application is about the same as your actual income in your tax return.
Actually, they are not the same since a huge portion of my stated income is "unearned" income from my family members. They deposit a chunk of money into my account several times per year (not following any certain schedule).
On my application, I had combined both of my earned and un-earned income, so I'm not sure if this would be okay with AMEX?