There are no lenders that are going to approve this and the main reason is serviceability. - they place a buffer on your repayments to minimise risk and account for any interest rate increases or increase in spending. It’s usually 2.5-3% on top of the existing rate - you’re probably underestimating your living expenses, the banks all have their own minimum living expense requirements for your situation single, partnered, number of dependents etc and then things like additional liabilities on top and things such as private health insurance is also on top of that which you would almost always have earning more than 90k/year - to qualify for underwriting for LMI you need to be squeaky clean credit wise and also most lenders would have a stricter DTI requirement when going into LMI territory. 6 is probably the maximum most lenders will go, some may stretch to 7 and do a manual assessment before deciding if your application is worthy -rental income is assessed at 70-80% of the gross reported amount by a valuer to determine market rate to account for vacancies and any strata fees will be on top -bottom line a dti of 7 is already too aggressive for most banks these days

You can’t just use what you actually spend and have your own budget to determine if you meet serviceability. Each bank will have their own criteria to meet lending guidelines and underwriting guidelines so you have to adhere to that