How do inactive credit cards affect your credit score?

"One of the most important factors in your credit score is the credit utilization ratio (often referred to as the debt-to-credit ratio). This measures the existing balance on your cards relative to your total spending limit, and reporting agencies use it to assess how well you handle credit.

That said, there is one way that maintaining a zero balance could hurt your score. Card issuers have been known to cancel cards after sustained inactivity, and if your account is closed, then you lose that portion of your total spending limit."

- http://thepointsguy.com/2016/02/should-i-use-credit-cards-monthly/

"If you’re holding onto a credit line that you’re not using, your credit card company would rather take it away from you and give it to another customer that will."

"Although the CARD Act of 2009 states that creditors must provide customers with 45 days notice of major changes to the terms of their accounts, courts have decided that a card cancellation caused by inactivity doesn’t count as one of those major changes."

- https://www.nerdwallet.com/blog/credit-cards/credit-card-cancelled-due-inactivity/


"Utilization contributes toward the amounts-owed portion of your FICO score, a scoring model commonly used by lenders. The amounts-owed factor counts for 30 percent of your score."

"The score wants to see some kind of activity"

- http://www.bankrate.com/finance/credit-cards/does-card-inactivity-hurt-credit-score.aspx

In summary:

• You must use credit cards and pay them off as agreed (making at least minimum payments) to build credit score. Now
• Credit utilization accounts for at least 30% of your FICO score. The lower the better - but to a point!
• No credit activity for a some cards can lead to card cancelation, which increases your utilization.
• No credit activity at all can hurt because zero activity = unpredictable = high risk.

So, not having any credit card activity is not ideal. If you have many cards and you want to stop using them, avoiding them permanently will cause them to be canceled by the issuer. Keep the ones you want active just by using them once every few months. As for the ones you don't want, cancel them after zeroing out your balance to avoid a hit to your utilization ratio. In general, having a long and positive credit history (healthy ratio) is more important than how much total credit you have at any given moment.