When you have income that exceeds $3,500 gross, CRA considers this to be Self-Employed earnings and requires you to report it on the T2125 - Statement of Business Activities. By reporting it here, TurboTax will calculate any CPP Contributions you must pay on those earnings, and post the Net amount to Line 13500 of the T1 General Tax Return.
To complete this form, you will need to enter the province of self-employment, your business address, your industry code. For the name of the business, you can simply use your own name.
Be sure to enter any expenses you may have incurred earning this income on the T2125 as well. Here's some information from CRA on eligible Business Deductions.
