No – you can also choose to pay in quarterly, half-yearly, or annually. Generally speaking we suggest paying in on a monthly basis, because we think that in order to extract maximum value from every dollar you invest and fully optimise your finances, having as many entry-points as possible is the best way to benefit from dollar cost averaging (DCA), and therefore in many cases, even if your income is earned quarterly/half-yearly/annually, it is best to invest it gradually each month. But the choice is yours.