Borrowing power: the rate you pay is only part of the test.

A property can look affordable at its advertised loan rate and still fail a bank’s borrowing test. The gap matters when we assess whether a development is financeable.

Borrowing capacity depends on income, expenses, existing debts and lender policy, as well as interest rates. No single number decides it.

One part of that test is APRA’s serviceability buffer: banks assess repayments at least three percentage points above the loan rate. This article separates that rule from the separate debt-to-income limit and illustrates the effect of changing one assumption.

What the serviceability buffer is

When a bank assesses a home loan, it does not test your repayments at the rate you will actually pay. It tests them at a higher rate.

The Australian Prudential Regulation Authority (APRA) expects banks to add a serviceability buffer of at least 3 percentage points to the loan rate. For example, a 6% loan has a minimum 9% assessment rate under that buffer; a lender may apply a higher rate or other requirements.

This provides a safety margin. It does not guarantee that a borrower will be able to meet every future repayment.

Two different checks, two different questions

Serviceability asks whether assessed income can cover stressed repayments and living costs. Debt-to-income compares total debt with gross income. Passing one check does not mean a loan passes the other.

APRA reaffirmed the 3-point buffer in its 28 May 2026 policy update. The buffer allows for adverse changes in rates, income and expenses. Our reading is that a development feasibility should remain separate from a lender’s approval decision.

What a one-point change would do

A simple worked example. Same borrower, same income, same expenses. Only the assessment rate changes.

Illustration only. 30-year principal and interest loan. Each lender runs its own full serviceability model.

In this example, one point of buffer is worth about $58,000 of loan, close to 10%. Nothing else about the borrower changed.

That is why we watch the buffer as closely as the cash rate. It is a lending rule, not a rate decision, so it can change without an RBA meeting.

How new dwellings fit into the DTI limit

Since 1 February 2026, APRA has also applied a debt-to-income (DTI) limit. Loans at six times income or more are capped at 20% of each bank’s new lending, measured separately for owner-occupiers and investors.

Qualifying loans for construction or purchase of newly erected dwellings can be excluded under APRA’s definitions and reporting rules. Smaller banks may choose not to carve out exempt loans. This does not remove serviceability checks or guarantee approval, and a rooming-house proposal should not be assumed to qualify.

What we see

Nobody knows when, or if, the buffer comes down. Anyone giving a date is guessing. Here is how we read the current settings:

• Recognised income matters. Lenders may include rental income in their assessment, subject to their own policies. Multiple room rents may be treated differently from a conventional tenancy.
• Expected capital growth does not pay current repayments. Rental income may support a serviceability assessment, but lenders apply their own discounts and policies. A higher advertised yield does not guarantee a larger loan.
• The new-dwelling exclusion has conditions. Eligibility depends on the loan category and the lender’s implementation.
• We treat a buffer cut as upside, not the plan. Our assessment approach is to use current settings rather than assume future easing. If APRA moves, that is a bonus.

This is why we build purpose-designed rooming houses: several room incomes from one title, with a target of positive cashflow. Actual cashflow depends on occupancy, operating costs and finance terms; it is not guaranteed. See what positively geared from day one means, how interest rates flow through to yield, or explore a simple income illustration with our rental yield calculator. The calculator does not assess borrowing capacity. Our Rooming House Method explains our development process and service scope.

If you own land and can’t borrow to build

For a landowner, a site’s development potential and the availability of construction finance are separate questions.

Holding costs can continue while a site is unbuilt. Our view is that comparing its sale value with a costed development scenario can clarify the options. Development also brings funding, approval, construction and selling risks; it is not automatically the better outcome.

What would prove this wrong

Our example isolates the assessment rate. Its borrowing-power uplift would not carry through if another constraint, such as recognised income, expenses, a lender floor rate or the DTI limit, became binding. It is not a prediction of a policy change or an individual loan result.

We would revisit this analysis if APRA changed its settings or lender treatment of the proposed income differed from the assumptions. We do not assume that more potential rent automatically means more available finance.

Common questions

Primary sources: APRA: serviceability assessment (2021); APRA: debt-to-income limits and exemptions; APRA: settings reaffirmed, 28 May 2026. Checked 28 September 2026.