Record Retention
How Long You Should Keep Your Records: According to the CRA, you should keep your tax documents and supporting records for at least six years after the end of your tax year, we recommend that you keep everything for seven years, just in case you need it. This time period applies to both business and individual taxpayers.
Which Records You Should Keep: You will need to keep all T slips and back up related to tax credits claimed; this include and not limited to medical expenses receipts, public transit receipts, invoices and bills. If you own a business you need to keep a copy of the financial statements used to file the corporate tax return and the backup paper work used to prepare the statements including and not limited to: ledgers, receipts, invoices and other supporting documents.
For more details please visit the CRA Books and Records Retention/Destruction circular: www.cra-arc.gc.ca/E/pub/tp/ic78-10r5/ic78-10r5-10e.html