Imagine that you’re migrating new contact and company records from Salesforce to HubSpot in a single import file. In the import file, you include the Salesforce account ID as the unique identifier. What will the unique identifier be used for?

When you are importing multiple objects (such as both contacts and companies) in a single file, HubSpot relies on a shared unique identifier—like the Salesforce Account ID—on each row to know exactly which contact belongs to which company, allowing it to associate records automatically during the migration. While unique identifiers can also be used to de-duplicate individual records of the same object type during an upload, the primary reason a third-party CRM ID (like a Salesforce ID) is included when migrating combined object types in one spreadsheet is to stitch the relationships together.