Jennifer writes in: Yesterday, I received a notice from [my credit card company] that my credit limit had been lowered from $10,000 to $4,000 on my primary credit card. I was immediately worried that my credit had been damaged by identity theft, so I checked it on annualcreditreport.com and there was nothing there at all. I’ve always paid all of my bills on time and my life has been pretty much normal and unchanged for a long time. Why would they make this change? I’m not concerned about reaching my credit limit, but that reduction in my limit does alter my debt-to-credit ratio, which could negatively impact my credit rating. Jennifer describes a pretty typical scenario today. A credit card company sends a letter out of nowhere, for no obvious reason, announcing a significant drop in one’s credit limit. One big effect that such a drop has is that it alters your debt-to-credit ratio, as Jennifer mentions. Simply put, your debt-to-credit ratio tells what percentage of your credit limit across all of your credit cards you’re actually using. So, let’s say Jennifer had a $3,000 balance on her $10,000 card – that’s a 30% debt-to-credit ratio.

Read more here – Why Was My Credit Limit Lowered?