Hello, thanks for reaching out

If you have claimed Capital Cost Allowance (CCA) in the past on your vehicle used for Business or Employment, you will have a number left at the end of the year known as Undepreciated Capital Cost or UCC. 

If this is your first time claiming CCA on that vehicle, you will not have a UCC amount. UCC is the balance of the capital cost left for further depreciation at any given time. 

For example, if you claimed the full 30% CCA on a $10,000 vehicle last year, your UCC would be $7,000 

( $10,000 - $3,000 = $7,000 UCC)

https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-re...

Hope this helps!