Under the new regulation, authorized deposit-taking institutions (ADIs) will be restricted to issuing no more than 20% of new home loans to borrowers whose DTI ratios are six times or higher. This cap applies to both owner-occupier and investor loans but notably excludes new housing developments. Currently, approximately 6% of new loans exceed this DTI threshold, with nearly half of all new loans falling between four to six times the borrower's income.

APRA Chair John Lonsdale emphasized the proactive nature of this measure, stating that the regulator aims to mitigate high-risk lending before it poses systemic threats. Given the Australian banking sector's substantial exposure to residential mortgages, such preemptive actions are deemed necessary to safeguard against potential housing-related shocks.

This policy marks APRA's first adjustment to loan regulations since 2017, aligning Australia's approach with similar measures adopted in countries like New Zealand and Canada. The decision follows a series of interest rate cuts and government incentives for first-home buyers, which have contributed to record property prices and an 18% surge in investor loans in the last quarter.

For prospective homebuyers, particularly those considering car loans in conjunction with mortgages, it's crucial to understand how these changes might affect borrowing capacity. High DTI ratios can limit access to additional financing, such as vehicle loans, as lenders assess overall debt obligations more stringently under the new guidelines.

In light of these developments, borrowers are encouraged to review their financial positions and consult with financial advisors to navigate the evolving lending landscape effectively.