I just bought mine this year. I got in by the skin of my teeth as a single person in a ridiculously expensive capital city.

In Australia we have things called Offset accounts. This is a regular bank account that you might get your salary paid into, but it's linked to your mortgage loan. The interest you pay on the mortgage is based on the mortgage principal minus what's in your offset.

So if my mortgage is 500,000, and I have 50,000 in my offset account, interest is only calculated on 450,000. I still have access to my $50, 000 to do with as I please, but the more I stack up there,the less I pay in interest, and the less that interest compounds.

So for these first few years it's really important for me to stack as much cash in my offset account as I can, because it will save me huge amount of interest over the life of the loan.

I'm working two jobs, 7 days a week for the first couple years to do that, and I have a couple other side hustles to help reduce cost of living as well. But the bank is still making a killing off me in interest.

I would rather die than be a landlord though, so I have an agreement with my partner. Instead of contributing to the mortgage or paying rent, she loans me a set amount each week, say, $300. This builds up in my offset account and helps reduce the interest I pay. After 5 years, I'll repay this loan to her at the same rate, $300 a week.

This benefits us both hugely, she will effectively have a rent-free period of 5 years AND be getting a boost to her cashflow, while I will have been able to offset my mortgage by up to 78k extra over the course of 10 years.

Yes, she will effectively 'lose' the opportunity to earn interest on her savings by saving that money herself for 5 years, but she won't lose the principal amount, and together we will have robbed the bank of far more interest than she would have earned from saving it.