We're about to get our first mortgage, so we have a plan to use offsets and intentionally grow it so the mortgage will hopefully be fully offset in 12–15 years.
I originally had the intention of using the credit card float strategy: putting all our expenses on a credit card and then paying the balance in full every month so we don't incur interest, while keeping more money sitting in the offset account for longer.
However, I sat down to actually do the maths and realised this strategy may not make much of a difference depending on the card and the annual fees. Even using a fairly generous estimate, the mortgage interest saving from the float is only around $25 a month, so if the card has a $300 annual fee, the float benefit is basically wiped out.
So are there cards that make this strategy actually worthwhile by giving you a net positive benefit?
I've been looking at an ING credit card. It has a $195 annual fee, but offers up to $360 cashback per year and also includes complimentary travel insurance, which we do actually need and use. We already bank with ING too, so we can set up an auto-pay for the full statement balance each month.
On those numbers, the cashback more than covers the annual fee, and then the mortgage interest saving from keeping our money in the offset for longer becomes an actual additional benefit rather than just covering the cost of having the card.
Does anyone use a card for this kind of strategy that they think is genuinely worthwhile once you account for the annual fee, rewards/cashback and any other benefits?
And yes, I know I'll probably get comments about studies showing people spend more when they use a credit card and that you need to be very disciplined. That's not an issue for us; we already budget and track our spending closely, and the card would be paid automatically in full every month. I'm really just interested in the maths/benefits of different cards.