Four years after the STM introduced the Opus card, it may be time to get yours replaced.

As many as 3.8 million of the public transit passes have been issued since April 2008. Early adopters of the transit pass will need to buy a new one before April 2012.

"It's a bit like bank cards and credit cards," explained Isabelle Trottier, spokesperson for the STM. "You receive a new one every four years."

Almost 200,000 people will be required to replace their Opus cards before the end of 2012.

Replacement of the card is free, but must take place within three months of its expiry date.

"We want people to come ahead of time so they are not stuck in a bad situation. And as it's free of charge, we encourage people to be proactive," said Trottier.

Expiration dates may be checked at an Opus machine, at a retailer selling the cards, or online.

Any fares on the existing Opus card may be transferred to the new one. Replacement cards must be purchased at a specific service point.

"We have six points of service," explained Trottier. "Berri-UQAM, Honore-Beaugrand, Jean-Talon, Cote-Vertu, Lionel-Groulx and the Fairview shopping centre."

Anyone unable to visit those six service points may also be reimbursed by mail, by buying a new card and sending the old Opus pass with a receipt to the STM. The address can be found here

The STM will begin issuing a new generation of OPUS cards this summer with a written warning indicating the card will expire in four years.