Should I split the cost of the home we purchased in 2017 and then sold in 2021 50/50 on the adjusted cost base line for my wife and I?

Both of you will need to report the gains on your tax return and split it based on your investment in the property.  For example, if you and your spouse each own 50% of the house, you would split the gains 50 – 50 on your return. If that is the case for "adjusted cost base cost" and total "proceeds of disposition" you would have to put in half the total for each partner.

For more information read TurboTax Article: Can I Split My Capital Gain With My Spouse? 

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