GO Transit riders who've been using monthly passes will have to switch to the Presto card after Jan. 1. (WikiCommons)

Starting on Jan. 1 GO Transit riders will no longer be able to purchase monthly passes.

Instead, GO riders will have the option of using Presto — the reloadable electronic fare cards — or pay their fares for individual rides.

GO says the switch to Presto won't cost riders more money, because the card includes a discount for multiple trips.

GO Transit said the sales of monthly passes have been gradually decreasing since the introduction of Presto. In September 23,500 monthly passes were sold, which accounts for 18 per cent of GO regular commuters. 

Judy, a regular GO Transit user, told CBC's Trevor Dunn she finds the Presto cards convenient. She prefers to use a payment option that automatically tops up her card.

"I work a four-day week, so monthly passes don't make sense for me," she said. "So the Presto works fine. As soon as it gets down to $20, it automatically loads up again."