We closed ours the minute they were paid in full because we never wanted to deal with credit cards again. That was in 2014. Aside from having a mortgage, we have no debt, and our scores are above 800 but that's only because we make our mortgage payments on time. And, if it weren't for a recent refinance when rates went super low, I couldn't have told you what our score was because it isn't something I track. In fact, we keep our credit frozen to help decrease the chance of identity theft. As others have mentioned, it's a personal preference and should be in line with your end goal (i. e., we never wanted to borrow money again so closing all credit lines was in line with our overall goals).