You should have recorded in your cash books all amounts you have actually received and payments you have actually made. However the cash books may be incomplete as your bank may have put extra transactions through your account such as:
► bank fees or interest charges
► direct debits (payments) and direct credits (receipts).
Doing a regular bank reconciliation will allow you to:
► take into account any extra transactions your bank puts through your account and
► check and record any errors or omissions.
By regularly doing a bank reconciliation (say monthly) you can be more confident that your records contain all the information you need to prepare your income tax return and activity statements.