The general rule on migration is that whatever transactions happen on one backend are billed through that operator. That means any transaction prior to the migration will be billed through the previous operator. Any transaction taking place on the CentralNic system will be billed through the CentralNic system.
While this is generally true, transactions that are still in-grace (AGP/RGP) are an exception to this rule...
Domains that are in grace period on the time of the migration will be billed through the CentralNic system if they are correctly flagged in the escrow deposit. On import, we rely on the "rgpStatus" flag in the escrow deposit:
Let's have a look how different scenarios are handled:
addPeriod - The domain is in AGP due to recent registration: CentralNic will bill for this domain once the RGP is over
- autoRenewPeriod - The domain is in RGP due to recent auto-renew: CentralNic will bill for this domain once the RGP is over
- pendingDelete & redemptionPeriod - The domain is marked as Deleted and will be purged from the Database after RGP is over. Note that since we don't know the exact deletion date, we use the date of import, so domains will be deleted 45days after migration. No billing will be done on CentralNic side.
renewPeriod & transferPeriod - The domain was recently renewed or transferred. We ignore these as we don't know the time of transfer or the period for the renewal. The registry operator should provide a list of these domains including dates and periods in case these should be billed through CentralNic.
NOTE: Please confirm with your previous backend operator that these flags will be present in the deposit and that they will not double bill for transactions that will be created on the CentralNic side.