Every name, income, debt, transaction, document, timeline, lender reference, and outcome here is invented. This is not a real client story, lender assessment, approval, recommendation, testimonial, or prediction.
The shared hypothetical setup
- Mortgage principal: $600,000
- Revolving-credit limit: $20,000
- Illustrative interest rate: 6.0% per year
- Illustrative term: 30 years
Only the revolving-credit balance pattern changes. Real products have their own rates, fees, repayment rules, lender criteria, and suitability questions.
Ollie
Ollie — commission-heavy Auckland income, status-conscious spending, and optimistic next-payday assumptions.
Ollie’s Huffer, Nike, Apple, Uber, weekend-trip, and social spending often lands in the revolving facility. The limit becomes available spending rather than a cash-management buffer.
Average facility balance: $12,291.67Month 12 balance: $18,500Illustrative 12-month interest: $737.5A flexible limit can become a second credit card when discretionary spending is allowed to refill it.
Hannah
Hannah — disciplined Dunedin nurse with stable base pay, variable overtime, and convenience spending after long shifts.
Hannah routes pay and planned bills through the facility, then leaves the surplus against the balance. Meal-prep, savings, and a rule for shift-related convenience spending keep the balance moving down.
Average facility balance: $1,391.67Month 12 balance: $0Illustrative 12-month interest: $83.5The same product can behave like a cash-flow tool when the balance is deliberately reduced and the limit is not treated as income.
Balance over twelve months
Illustrative maths only: monthly interest is calculated as balance × 6% ÷ 12. It excludes fees, compounding, rate changes, repayment rules, and every other household circumstance. A lower simulated balance is not a recommendation or approval signal.
Questions the simulation raises
- What rule keeps the facility balance moving down?
- Which spending is genuinely planned, and which is borrowing?
- What happens if income arrives late or a large annual bill lands?
- Would a different structure be easier for the household to manage?