Only the amount of the unearned income above $2,100 (for tax year 2015) is taxed at the parent’s rate, right? So if the asset was sold over multiple tax years, each year the child could take advantage of 0% tax on the first $1,050 of gain, the next $1,050 of gain taxed at the child’s rate (presumably 10%), and everything more than that taxed at the parent’s rate. Of course, if the child also has dividends and/or capital gains distributions to report, maybe none of this would make much difference anyway.