How do Canadian immigrants prove their self-employed work experience?

If you run a company, you can provide the company's business license, tax bill and so on. If there is no company, you must have a letter of recommendation from the relevant recommender, explaining the situation and whether you have paid taxes during your self-employment. Then there are tax bills, bank card income, or your job content, such as translation, which can be used as evidence for customer translation, and so on.