This can all be found right in the CapOne credit line increase FAQs
http://www.capitalone.com/credit-cards/credit-line-increase/
Are all Capital One cards eligible for credit line increases?
Some accounts are typically not eligible for increased credit lines upon request, such as accounts that are less than three months old, and accounts that have received a credit line increase or decrease in the last six months.
While these types of accounts are usually ineligible for credit line increases upon request, other accounts are not guaranteed to be approved.
What factors determine if I’m eligible for a credit line increase?
When considering an account for a credit line increase, we may look at a variety of factors such as your on-time payment history, average monthly payment amount, credit bureau information, and credit score. We also may look at whether you use a significant portion of your existing credit line. If you regularly use your card and make payments on time, it builds your account's payment history. If not, we may not have sufficient payment history to review.
Two of the important factors that help determine your eligibility for a credit line increase are in your control: on-time payments and making substantially more than your minimum payment every month. We want to make sure you’re able to make the increased payments that may be required if you used your increased credit line. So, using your card responsibly by having a solid history of making on-time payments and making more than your minimum payment are two ways you can improve your eligibility for a credit line increase.
