Error: CMN.ATO.IITR.40044 - Spouse's or de facto spouse's first name must not exceed 15 Characters.

Solution: Make sure to unlock the form first,  change the name according the instructions below (from the ATO) and try to lodge the form again.

"The validation rule has a character limit of maximum 15 we recommend that the user will space out the name under 'Other given name' which has a character limit of 40. It is up to the client on how they want to split their name between "First name and "Other given name" fields.

Illustration.

Client name is: Mahershalalhashbazcher

Workaround should be, "Mahershalalhashbazcher" will split under "First given name" and "Other Given Names"

First name: Mahershalalhash

Other Given name / Middle Name: bazcher