https://help.gosimpletax.com/hc/en-gb/articles/360000590870-Foster-Carer-or-Shared-Lives-Carer
If you are a Foster Carer or a Shared Lives Carer, you can show this on your Tax Return, Self Employed Page
Add the Self Employed Page
Click on the EDIT button
Select the Foster Carer Radio Button
Click SAVE