Betterment Charitable Giving will enable you to donate shares with long-term gains that have been held for more than one year from the day of purchase. In the “Give to charity” flow, we will calculate the dollar value of those eligible shares. You can donate any dollar amount you would like up to the eligible amount. Our algorithm will automatically select the shares to give with the biggest potential tax benefit.
Note that each additional share purchase (including new deposits, reinvestment of dividends, tax loss harvests) has its own one-year period until it becomes long-term.