Yeah I don't have a cent of savings to my name in Hong Kong and manage all my day to day expenses with an overdraft for which i am paying around 1%-2%. So I always have a negative bank balance and it's just a matter of how much negative money I have in the bank. My idea of "saving for a rainy day" means not having my overdraft maxed out to it's limit and being able to borrow more should I need to. So having to pay my April tax now has just extended my overdraft to somewhere getting a little bit uncomfortably close to it's limit and costing me 1-2% for 3 months (as well as the lost HSBC promo)
This sounds pretty stupid on the face of it, I know. But the fact is I have property and mortgages in Australia for which I am paying 5%-6% interest and they have those 100% offset savings accounts. So all of my cash is just sitting there in Australia saving 5-6% and in HK I borrow as much as I can right up to the limit at only 1-2%. Every cent I can borrow in HK saves me money. HK is a low interest rate environment that makes little sense to hold any cash here if you have assets and debt in other higher interest rate countries.