If your client has a taxable Betterment investing account, simply have them log in to their Betterment account on their desktop computer. On the Transfer tab, select “Give to charity.” They can then specify how much they would like to donate and which partner charity they would like the donation to go to.
After the gift is initiated, they’ll be prompted to make an optional deposit, which would replace the donated shares to keep their goals on track, and potentially avoid a rebalance.
Read more about donating shares here.