See Spouse Details item SD on the ATO website.
If you had a spouse during the current income year, you must complete Spouse details. If you do not know the spouse's taxable income then you should make a reasonable estimate.
If your spouse's details are in the data base then click label K to open the Select Return index and automate the completion of all the spouse's details and income.
You should use the F10 feature to avoid incorrect data entry for the spouse and consequent F3 validation errors.
To complete the details click any label at SD L to F to open the Spouse Details dialog and enter the details.