Cost or book value is total amount paid to purchase a security, including any transaction charges related to the purchase, adjusted for reinvested distributions, returns of capital and corporate reorganizations. The preparer is expected to take reasonable measures in order to ensure that the amount reported in box 20 is correct. Do not enter the market value or the current price the asset was sold for in box 20. The investor needs this amount to calculate the adjusted cost base (ACB) of the security or debt investment and to track gains (or losses).

This amount may or may not reflect the investor's ACB for the purpose of determining their gain or loss from the disposition of the security. The investor should be aware that they may have to make adjustments to the amount indicated in box 20 at the time of determining and reporting their gain or loss from the disposition.