This morning I woke to the news that my favourite Australian mobile carrier, amaysim, have made some changes to their Unlimited plans. Great - more data, extra international call allowances, what’s not to love?! Turns out, they’re switching to a 28-day billing cycle. This is becoming increasingly popular in the Australian phone plan market, and I’m here to tell you why it matters.

I am not a fan of this new “trend” towards 28-day billing cycles on mobile plans, generally on prepaid or “no lock-in” services. While some people may look at it and think, “It’s only two days less, that hardly makes any difference,” there is something to worry about. Now it’s great that amaysim are increasing the data allowance per month at no ‘additional cost’ however you aren’t getting this extra data for nothing, and let no one tell you you are.

Lets analyse the whole 28-vs-30 day billing cycle for a moment…

If you’re paying $39.90 (the price of the most popular amaysim Unlimited plan) per recharge - or billing cycle - you pay $485.45 for a years worth of service. This figure was calculated by multiplying the price per month by the amount of recharges per year - in this case 12.17 (30 goes into 365 approx. 12.17 times). This ends up being $5.45 more per year than someone who pays every “month” where the billing cycle begins and ends on a set date per month. No biggie. But lets compare that to paying per 28 days, you will recharge 13.04 times per year, paying $520.13 - that’s $34.68 more over the course of a year, nearly the cost of a whole extra recharge.

Now I know that 30-odd dollars isn’t much, and that it shouldn’t really warrant a complaint, however I just wanted to make it known that these changes are significant. Particularly for someone with limited budget who thinks they’re paying $39.90 per month for service, when in fact they’re paying $43.34. It isn’t just amaysim, but by moving to 28-day billing cycles all of the carriers including the big three - Telstra, Optus, and Vodafone - with their prepare plans, manage to squeeze nearly a whole extra recharge out of each customer per year. Just keep that in mind when you sign up for a mobile plan on a 28-day billing cycle.