Your credit card is only charged when a campaign you pledged to ends successfully, not at the time of placing the pledge. When you pledge to the project, we will send you an email to confirm your pledge is placed, then when/if the campaign ends successfully, your card will be charged in that amount.
At the time of placing your pledge, you may see a pending authorization on your statement though if the campaign does not reach 80% of its funding goal, your card will not be charged and that pending line will fall off.
If your card is declined for any reason, you'll receive a notification on how to update your payment details and fix the pledge. This will happen after the campaign is complete.