Should the highest balance not increase, then the saver would not earn a final bonus.
With the most a person can pay into the account each calendar month being £50, this works out at a maximum of £2,400 over four years.
Gov.uk explains that the most a person can earn from their savings in four years is £1,200 in bonus money.
“Frankly it’s totally unbeatable if you’re eligible and it goes slap bang at the top of my rate-o-meter,” Mr Lewis said tonight.