Two applicants with similar incomes routinely receive very different credit limits, which suggests the number is not a simple function of earnings. A limit is a loss estimate, not a reward.
The limit is an exposure decision
A card limit is the maximum the issuer is willing to be owed by that customer at any moment, so it represents the size of the loss the lender would absorb in the worst case.
Because the lender is unsecured, there is no asset to recover against, and the entire outstanding balance is at risk if the customer stops paying. The limit is therefore set against expected losses across a whole group of similar customers.
Profitability enters the same calculation. A limit large enough to be useful generates more interest and interchange, so issuers are balancing potential loss against foregone revenue rather than simply minimising risk.
Income matters less than capacity
Lenders care about disposable capacity rather than gross income, so declared earnings are reduced by known housing costs, existing loan payments and the assumed cost of other credit lines already held.
An applicant with a substantial salary and several large existing commitments can show less capacity than someone earning considerably less with no other obligations. The residual figure is what the assessment works from.
Undrawn credit counts against capacity too, because an unused limit elsewhere could be drawn tomorrow. This is why closing unused accounts sometimes increases what a new lender is prepared to offer.
Behaviour is more predictive than status
Repayment history carries more weight than income in most scoring models, because past behaviour under stress predicts future behaviour far better than a current salary does.
Patterns matter as well as missed payments. Utilisation that sits permanently near the limit, frequent cash withdrawals, or a run of recent applications all raise the assessed probability of difficulty.
A thin file produces caution rather than generosity, since the lender has nothing to model. Low opening limits on first cards reflect absence of evidence rather than a negative judgement.
Limits move after the account opens
Issuers reassess accounts continuously using their own repayment data, which is richer than anything available at application, and adjust limits as that behaviour accumulates.
Increases are commonly offered to customers who use the card regularly and clear balances reliably, because those customers generate revenue with low expected loss. Reductions follow deterioration in the same signals.
A limit can also be cut when broader economic conditions shift, since issuers manage total exposure across their portfolio rather than judging each customer in isolation.
What a requested increase is assessed against
Asking for a higher limit triggers a fresh affordability assessment, and the outcome depends on updated income, current obligations and the account's recent conduct rather than on how long the account has existed.
A request can be refused without the existing limit changing, but it can also prompt a review that leads to a reduction if circumstances have visibly worsened since the account opened.
Because the assessment is about capacity, the most effective preparation is reducing other outstanding balances rather than demonstrating heavier use of the card itself.