How to calculate business income work in progress end/start of year?

Work in progress (WIP) includes any work that has been completed but has not yet been billed to the client. WIP only needs to be calculated if your business is of the "Professional" type. 

Professional and business income are both reported on Form T2125. However, because of differences in the way professional income is calculated, not all businesses are considered professions for tax purposes. Professional includes the following:

• Architect 
• Chartered or Certified Accountant 
• Dentist 
• Engineer 
• Lawyer or Notary 
• Management Consultant 
• Physician, surgeon, or specialist 
• Psychologist 
• Veterinarian 
• Other accounting or bookkeeping services 
• Other health practitioner 
• Other scientific or technical services 
• Other social service practitioner 

CRA considers other self-employment income (as long as it's not from farming or fishing) to be business income rather than professional income.