So long as you sent your invite for the relevant tax year to your client's correct email AND your client logs into Intuit Link for the year for the first time by clicking on the button within your invite (which contains a token) and using the email address to which the invite is sent as the User ID (which should be populated automatically by the browser), your client's Intuit Link account will be connected to yours.

Problem occurs when clients who have an existing Intuit Link account try to log into Intuit Link for the new year merely by using the credentials without following the steps outlined above.