Maximum risk is the difference between the strikes MINUS credit received. For GOOG that could be $1000.00 - $200.00 = $800.00. My guess is that your broker would never allow the long leg of your position to be closed before the short position. If one of the legs is approaching ITM then you should close both legs to minimize your loss, and don't wait till expiry.
yes I know but I'm trying to understand what happens IF. I also know how to calculate my risks but I dont understand "stock assignments" that are automatic.
It's all a Moot Point. Your credit spread should have been closed before you end up with ITM options. ------
All it takes is a web search on "option assignment" and you'll find a gazillion explanations. Here's the first one on the list: http://www.optiontradingpedia.com/options_assignment.htm