ShareGate Migrate carries your associated permissions during migration and will attempt to preserve their integrity from the source to the destination whenever possible.
This article explains what happens to your permissions when running a Copy content only migration.
Note: When you migrate to a site associated to a Microsoft 365 group, note that the owners of your group are automatically granted site collection admin permissions on that site. This means that they have access to everything in the site, including items with custom permissions.
Index
Users and groups association (automatic mapping)
Your users and groups are automatically mapped at the destination. This association is done through the SharePoint people picker to preserve your permissions, and Person or Group metadata values.
Permissions on documents, folders, and list items
By default, we try to preserve the permissions as they are on your items.
You can choose not to keep the custom permission on your items using the Configuration menu in Copy Options. This will restore inheritance on all the items at the destination.
Preserve inherited permissions
If items have inherited permissions at the source, we will let them inherit the permissions from the list or library at the destination. If the parent item does not have the same permissions at the source and the destination, the migrated items will not have the same permissions at the source and the destination.
To preserve the list or library permissions from the source, you can:
Copy the entire list or library using Copy structure.
Configure a folder with the correct permissions at the destination and migrate to this folder.
Migrate the parent folder that contains the permissions to the destination, then migrate the items.
For more information on how to perform these migrations, see Copy content - Preserve inherited permissions.
Note: Custom permissions are only copied for the items they are associated with. If you uncheck preserve custom permissions in your Copy options, you will have to re-copy the items with the associated permissions again should you decide you want the permissions (you cannot copy permissions separately at a later time). Incremental copy will not bring over new permissions from the source since the permission change doesn't leave a timestamp (modified) on the item in SharePoint.