You may see one of these errors:
Must be related to an individual with a National Insurance Number
No owner listed in relationships
These errors can occur when the client doesn't have an individual owner with a valid National Insurance number linked.
Go to the client's Relationships section.
Add the client as an individual owner.
Enter the correct National Insurance number.
Save your changes.
Try connecting to HMRC again.
If you use Sage for Accountants, check the client's individual record links to their organisation record.
For landlords, also check that the business type matches the client's HMRC record.