The Credit Card Limit
Capacity Drag Calculator
See exactly how much home buying power is being suppressed by the combined limits of your unused credit cards. Lenders assess your limit, not what you owe.
✅ Current as of 16 June 2026 · estimate only · not a credit quote
Your Card Limits
The Underwriting Penalty
+$71,000
Calculated using inverse debt amortisation tables at an illustrative 9.5% stressed assessment rate over a 30-year term.
Walkthrough video — coming soon
A short walkthrough showing how credit card limits drag borrowing power and how reducing them frees up serviceability will live here.
The Credit Limit Illusion: Why a Zero-Balance Card Still Reduces Your Borrowing Power
A common surprise for premium earners: a credit card with a $0 balance — even one that never gets used — can still reduce how much you're able to borrow for a home.
That's because most lenders assess your credit limit, not your balance. Many lenders treat a percentage of your total card limit as an ongoing monthly commitment when working out serviceability, even if you clear the card in full every month. The exact percentage varies by lender (commonly around 3% to 3.8% of the limit).
How the limit translates into lost capacity
- Worked example: at a 3% assessment rate, a $25,000 limit is treated as roughly $750 per month of commitment. Once that's run through a lender's stress-tested serviceability calculation, it can reduce borrowing capacity by a meaningful amount.
- It's the limit that counts: reducing your limit (or closing a card you don't need) can free up serviceability — but the right move depends on your full situation and the lender.
These figures are illustrative. The percentage applied, the stressed rate, and the resulting capacity all vary by lender and by your circumstances.
How we help
We review your card limits as part of your overall position and, where it makes sense, help you reduce or restructure them in the right order before you apply. Closing or changing facilities at the wrong time can complicate a credit file, so timing and lender choice matter. We'll map a clean approach to your situation.
Built by Virginia Graham Riches, founder of Model Mortgages, supported by a specialist team of five mortgage brokers.
Frequently asked questions
Why do lenders assess my credit card limit instead of my actual balance?
Lenders look at your credit limit because it represents the maximum debt you could theoretically draw down instantly. Even if your statement balance is $0, you could spend up to the limit the day after your loan settles. Therefore, underwriters write their calculations against the aggregate limit, not the current balance.
How do lenders calculate the monthly commitment from my credit card limit?
Lenders apply a standard assessment factor—commonly between 3.0% and 3.8% of the total limit—to calculate a synthetic monthly commitment. For example, at a 3.0% rate, a $25,000 limit is treated as a permanent $750 monthly expense on your application, regardless of whether you clear the card to zero every fortnight.
Does closing or reducing my credit card limit automatically increase my borrowing capacity?
In many cases, yes. Lowering your card limit or closing unused facilities reduces your assessed monthly commitments, which frees up surplus income to service your mortgage. However, closing cards can sometimes affect the stability history on your credit profile, so timing and lender choice are critical.
How does a credit card commitment reduce my maximum borrowing power?
Lenders assess serviceability by subtracting all commitments from your net income. The remaining surplus cash flow determines how much you can borrow. Every dollar of assessed credit card commitment directly reduces this surplus. When run through stress-tested interest rates (e.g. 9.5% over 30 years), a minor monthly commitment significantly restricts borrowing capacity.
Your real borrowing outcome depends on all five assessment pillars working together — income, expenses, assets, security and borrower profile. A strong result in one pillar can be cancelled out by a constraint in another.
To see how this fits your whole position — your full servicing picture on one side and this scenario on the other — and which other pillars are helping or holding you back, run the full diagnostic at Structur.