If you are not claiming CCA and you don’t have any additions or dispositions, you don’t need to put in the CCA information. And if the CCA isn’t benefiting you, there’s no need to claim it this year.
If you don’t claim CCA this year, then the amount remains in your UCC balance. Next year, you’ll only be able to take CCA for 2020, but it will be based on the current UCC balance. If you take CCA this year, your UCC balance will go down and next year, your CCA will be calculated using the new, lower UCC balance.
As to why it is lowering your refund, there’s a possibility that the CCA is effecting your eligibility for the Canada Workers Benefit (line 45300) or some other credit that’s based on income. You can make a copy of your return without the CCA on the My Returns>View All Returns page. Then you can go into the Detailed Summary of both copies and take a look at what has changed. You can see the Detailed Summary by clicking on the arrow under your balance/refund in the top right of your return. Then click on “View Detailed Tax Summary”. If you are preparing your return with a spouse/partner, there are links at the top of the page to switch between the two.
