They will not notify you when you go past the annual cap on any card. In my experiences with other flavors of AmEx, the actual cap was always less than the amount I would get from the website under "Spending year to date". My best guess for that discrepancy is that the bonuses and some credits are subtracted from the cap. The explanation from an AmEx agent was that the "Sum" on the website is incorrect or not up to date -- and I do not believe that was the case.