Hi!
The interest income flowing into the T5's and other related slips is coming from the financial institutions that manage your investment. if multiple T5's are issued, you will need to go back to each investment and understand the breakdown. I've included some sources to help understand the T5 slip and it's source.
The easiest way to get a T5 taxpayer slip online is through the financial institution that manages your investment or savings account. You can also get the T5 slip directly from your CRA My Account. (If you don't have an account with the CRA, you should create one as soon as possible.) Once you’ve logged in, you will find all of your different taxpayer slips under the "tax information slips" (T4 and more) section, including the T5.
Source:
1) https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-re...
2) https://turbotax.intuit.ca/tips/t5-tax-form-statement-of-investment-income-in-canada-395
3) https://www.canada.ca/en/revenue-agency/services/e-services/digital-services-individuals/account-ind...
Let me know if you need any further clarification!
- V
