I am trying to report capital gains from stocks by summarizing Box 20 and 21. Do I need to send in a detailed summary sheet? Is there an easy way to do this through TT?

[TurboTaxKim]

If you have a lot of T5008 slips and don't want to enter them all individually in TurboTax, you can add up all your T5008 slips and enter as one entry on the T5008 slip page. Double-check to make sure that the totals are accurate. Basically, add the amounts from box 20 on all of your T5008 and enter it in one T5008 slip in TurboTax. Do the same for box 21 and so on.

CRA is fine with it being filed this way, and as you cannot submit a summary with a NetFiled return (nor are you required to)keep your documents available if they request to see them.