Check the 75,000 mile Citibank AA thread. Biz allows a new card 90 days after opening a prior one but some people say it needs to be 90 days after closing a prior one. Also if you're using EIN instead of SSN (sole prop) it's easier. I opened a biz in May, canceled in July, and opened a new one in January, both with bonuses and both under my SSN.