http://www.cic.gc.ca/english/resources/tools/perm/express/intake-complete.asp
The following documents are mandatory for each work experience declared:
a reference or experience letter from the employer, which
should be an official document printed on company letterhead (must include the applicant’s name, the company’s contact information [address, telephone number and email address], and the name, title and signature of the immediate supervisor or personnel officer at the company),
should indicate all positions held while employed at the company and must include the following details: job title, duties and responsibilities, job status (if current job), dates worked for the company, number of work hours per week and annual salary plus benefits; and
if the applicant is self-employed, articles of incorporation or other evidence of business ownership, evidence of self-employment income and documentation from third-party individuals indicating the service provided along with payment details (self-declared main duties or affidavits are not acceptable proof of self-employed work experience).
If the work experience is in Canada, proof may include copies of T4 tax information slips and notices of assessment issued by the Canada Revenue Agency (the time period for these documents should reflect the work experience timeframe [e.g., work experience from 2006 to 2008 requires only documents from those calendar years]).
