The cost amount (also referred to as the adjusted cost base) generally refers to the purchase price.
During the year, you may have purchased and sold various properties within the category. Consequently, the "Cost amount at year-end" and "Max cost amount in 2021" may be different. If you didn't buy or sell anything, then those amounts should be the same.
E.g. At the beginning of the year you have three properties where the cost was $1000.
Therefore, your Max Cost Amount in 2021 would be $1150, but your Cost Amount at Year End is $1140.
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