When you post a contest, you will be asked the prize you want to award the winner.
Once you complete the details of your contest and post it, you will be informed of the payment you will make for the contest prize. The amount will be deducted from your account right away. The prize is safeguarded by Freelancer.com until such time when you decide to which freelancer wins your contest.
If you have available funds on your account, those will be used to pay for the prize. You can deposit to your Freelancer.com account prior to posting the contest.
All available payment methods are listed on the Deposit Funds page.