Monday is the first deadline for the CTA's transition to Ventra, its new fare payment system. Starting Monday, CTA riders will not be able to load money onto their Chicago Cards or buy disposable magnetic cards at rail stations.

This is not a deadline for Chicago Card Plus users, though, whose cards will continue to autoload until Nov. 14, the last day that Chicago Card Plus can be used on CTA.

The CTA said it has finished mailing Ventra cards to Chicago Card Plus users and riders with registered Chicago Cards who have verified their information.

But the agency said there is a "small number" of Chicago Card users whose contact information is incomplete in the Ventra system, so the CTA is emailing those users to update information so their Ventra cards can be mailed.

The CTA said there are 899,000 Ventra accounts, and as of Wednesday, Ventra was used for about a third of all CTA rides.

Here's what you need to do and know for Monday's transition deadline.

If you have a Chicago Card

>> If you have not yet received your Ventra card, load money onto your Chicago Card this weekend and use the card until you receive your Ventra card. You will eventually have to spend down your Chicago Card balance, though, because balances cannot automatically be transferred to Ventra.

>> Chicago Cards can be used until Nov. 15.

If you have a disposable magnetic card

>> Load unlimited passes onto Ventra cards, which can be purchased at rail stations and retailers including CVS and Jewel-Osco.

>> You can still buy disposable cards at retailers, just not at rail station vending machines.

>> You can still use cash on buses and purchase single-ride Ventra rail tickets for $3, up from $2.25.