I have a ppor loan and an offset attached to it where my salary goes and my personal expenses paid from. Recently I revalued my ppor and IP and created a separate loan(call it investment loan) with a new offset (call it investment offset) attached to it. As a result new loan and offset accounts contain money that is borrowed only and will be used purely for future investment(such as paying down 20% deposit, and IP expenses etc.). As long as I do not use this investment offset money for personal purpose and avoid putting any non-borrowed money into this offset account, is there any problem in claiming tax deduction for interest paid on investment loan? I have another IP and planning to re-value it and topup same investment offset account and increase investment loan by same amount. Can I repeat same for future valuations of all my IPs and PPOR? That is, can I keep topping up same offset account(and increase amount in investment loan) and keep using money from this offset to buy future properties and pay IP expenses and still claim 100% tax deduction for interest paid on investment loan? Please can anyone please point out what I am missing and where things can go wrong? Assumption: I will make sure never to put non-borrowed money in investment offset and never to use money from this offset for personal purpose.