Like a loan, banks decide how much your credit limit will be by evaluating each individual according, but not limited, to these factors:
Income: Banks will assess your income to check if you can pay them back (basing from your employment status).
Spending: Banks will assess your credit behavior via your credit score. A good credit score can help you get a higher credit limit and vice versa.
Your credit limit isn't set in stone. Here are ways that banks can change your credit card limit:
By maintaining good financial health: If you have a good credit behavior, banks will inform you when they increase your limit. You can either accept it or maintain your current credit limit.
By request: You can also request to change your credit limit by contacting the bank's customer service, informing your branch, emailing them, or at times making a request through your online banking account. Banks will then reassess your request based on the factors stated above.
You have to let banks know that you have a healthy credit behavior, and you can do this by:
Spending below your limit: Ensure you spend only 30% of your credit limit. This will imply that you are in good credit standing and that you will make payments when they're due.
Paying on time: Banks want to know if you have a good credit behavior, so always pay in full or the required amount on or before your due date.
A high credit limit means that banks trust you to pay your monthly bills on time. This doesn't mean you should max out your credit card. Always spend within or below your limit so that you won't be burdened with huge payments later on or hurt your credit score.