Question

If I were to hold back the stock, what would be my tax return? How is the realised after-tax return different if I sell the stock?

Answer 1

If you hold back a stock and not sell it, there is no realized return and hence the tax return would never include the stock. since you only pay tax when you actually sell the stock

If you sell the stock, you either make a gain or loss. You you make a gain, you pay the capital gains tax on the gain you made. This would called as realized gain since you sold the stock. On the other hand if you made a loss on the sale of the stock, this loss can be offset against other capital gains in your tax return.