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Answer:
If the card is expired, the system automatically advances the year by 3. That is the most common renewal that card companies use. In addition, by default UltraCart sends.out a email notification to the customer which contains a link that the customer can use to update their billing details (update card details along with the billing address.) See: Understanding Emails Related to Auto Order Processing and also the 

What time does UltraCart charge the Auto Orders when they are re-billed?

Auto orders start processing on the platform at midnight EST. The platform continues processing them until finished which can vary depending upon the volume to process on any give day. The goal being that all of them are processed before 7AM when the first east coast fulfillment houses open to begin preparing shipments. 

Related Documentation

Auto Order Processing Configuration screen (must be logged in to access)

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