Just to avoid doubt, if you are green now, and you qualify for Silver for first time in Aug31, you will need to have another 60,000 in 2months to attain gold. If you are already silver and you meant you will "requalify" by 31 Aug by getting 30,000 miles, you simply need additional 30,000 prior to your current silver membership expirary date. From your post, I can't ascertain which of these category you fall in.