The SILVA NGS credit system has two types of credit actions:

• Credit Deposits: receipt for adding or removing credits from the global SILVA credit pot. Negative values remove credits from an user account and positive values add credits.
• Credit Transactions: payment or refund a user makes to execute an Project. Every transaction has an target result ID. Negative transaction values are refunds back to the users account, positive values are payments.

Executing a project with status "created" does not charge the project owners credit account. Only when an user "executes" the project changing the status to "waiting for approval" he pays for it. The same for cancel projects, if an admin cancels a project the user who payed for it does not get any refund. Only when an user uses the cancel button an refund of the credits is done.