It depends on what exactly you are adjusting on your tax return. The T1-ADJ form provides instructions on how to complete the adjustment and what you need to include. As a rule, if your adjustment involves a specific "schedule", you need to include that schedule along with copies of all related slips.
https://www.canada.ca/content/dam/cra-arc/formspubs/pbg/t1-adj/t1-adj-fill-08-18e.pdf
