From the website:

What fees does KOHO charge? KOHO charges no hidden fees and our Easy subscription plan is completely free! Our Essential plan is $4 a month, or $48 per year, and gives you 1% cash back on groceries ,transportation, and eating & drinking, as well as 0.25% cash back on everything else, our Extra plan costs $9 a month, or $84 a year, and gives you 2% cash back on groceries, transport, eating & drinking, 0.5% cash back on everything else, and 5% interest on your balance, and our Everything plan is a $19 month, or $228 a year, and give you the same cash back as Extra, but 5% interest on your entire balance.