Interest-Only vs Principal and Interest for Canterbury Buyers

Canterbury buyers regularly ask whether to structure their mortgage as interest-only or principal and interest. Here is an honest assessment of both options for owner-occupiers.

How Each Structure Works

Principal and interest (P&I) means your regular mortgage payment covers both the interest cost and a portion of the principal. Over time, your outstanding balance reduces and your equity grows through repayments as well as capital growth. This is the standard structure for most owner-occupier home loans and results in the mortgage being fully repaid at the end of the term. Interest-only means your regular payment covers only the interest component. Your outstanding balance does not reduce. Your equity grows only through capital growth, not through repayments. After the interest-only period (typically two to five years), the loan reverts to principal and interest, at which point your regular payments increase to repay the principal over the remaining term.

The Cash Flow Difference

Interest-only payments are lower than P&I payments for the same loan amount, which can be a meaningful cash flow benefit in the early years of a Canterbury purchase. On an $600,000 mortgage at 5%, the interest cost is $30,000 per year ($576/week). A P&I repayment over 30 years at 5% is approximately $695/week. The $119/week difference may be significant for first home buyers managing tight budgets in the early ownership period.

The Trade-Off

The cost of interest-only is that you do not reduce your principal during the interest-only period. Every year of interest-only is a year during which your mortgage balance stays the same while property values (and presumably your equity) change only through market movement. If Canterbury property values stagnate or fall during your interest-only period, your equity position does not improve through repayments. For owner-occupiers with a long-term ownership horizon, P&I is generally the financially superior structure because it builds equity through repayments and reduces total interest paid over the life of the loan. Interest-only is more commonly used by investors managing cashflow than by owner-occupiers building long-term equity in their family home.

Bank Restrictions

Banks limit interest-only terms for owner-occupiers, typically to two to five years, after which the loan must convert to P&I. The P&I repayment after a five-year interest-only period on a 30-year original term is higher than if you had started P&I from day one, because you now have 25 years to repay the same principal.

For general information only. Always consult a qualified mortgage adviser about the right loan structure for your specific circumstances.