The best time to ask for a credit line increase is when you actually don't need one. For example, your credit increase request is more likely to be approved when you're making more money than you did when you originally applied for your credit card, or your credit score has improved. Credit card issuers generally want to limit risk. So if you ask for more credit when your credit score is poor, or when your credit is already near its limit, your request is likely to be denied.