BUSINESS FORMS: 

RC1 Request for Business Number (BN)
https://www.canada.ca/en/revenue-agency/services/forms-publications/publications/2-1/required-registration.html

RC59 Business Consent Form
https://www.canada.ca/en/revenue-agency/news/newsroom/tax-tips/tax-tips-2016/tax-professionals-cra-offers-faster-alternatives-rc59-business-consent-form.html

T1013 Authorizing or Cancelling a Representative
https://www.canada.ca/en/revenue-agency/services/forms-publications/forms/t1013.html

T4 Statement of Remuneration Paid
https://www.canada.ca/en/revenue-agency/services/e-services/filing-information-returns-electronically-t4-t5-other-types-returns-overview/upcoming-year-t619/t4.html

T4A, Statement of Pension, Retirement, Annuity and other income
https://www.canada.ca/en/revenue-agency/services/e-services/filing-information-returns-electronically-t4-t5-other-types-returns-overview/t619/t4a.html

T5018, Contract Payment Reporting System (CPRS)https://www.canada.ca/en/revenue-agency/services/tax/businesses/contract-payment-reporting-system-cprs.html