A credit limit increase (CLI) on your Citi credit card gives you more freedom to use credit without increasing your credit utilization ratio. You may qualify for an automatic increase if you have good or excellent creditworthiness and maintain low or no outstanding balances. These factors also hold you in good stead if you request an increase on your own.
You may request Citi for a credit limit increase online or over the phone. Whether Citi carries out a hard or soft credit inquiry to make a decision depends on the specifics of your case, so you might want to ask a Citi representative in advance. If Citi denies your request, it is possible to take corrective measures and ask again, or you can apply for a new card.