Credit card companies do not always "hard verify" your income by requesting pay stubs or tax returns, but they have sophisticated ways to ensure the number you provide is plausible. Most issuers use statistical models to compare your stated income against your occupation, age, and geographical location. If the figure you provide is a significant outlier for your demographic, it may trigger a "Proof of Income" request. Additionally, under the Credit CARD Act, issuers are required to consider your "ability to pay," which is why they ask for the data. While they might not check every application, lying on a credit card application is technically bank fraud. For existing customers, issuers may also monitor your spending and payment patterns; if you suddenly start spending far beyond your "stated" income, they might lock the account until you provide verification documents to prove you can handle the debt.