Betterment does not currently provide charitable donation cost basis information, but we may provide it in the future. Since Betterment only allows donations for appreciated investments held over 1 year, using a cost basis lower than the market value at the time of donation and a purchase date over 1 year ago is the only available way to move forward.
In general, if you donate shares that have appreciated in value since the time of purchase and that you have owned for more than one year (which is the case when you donate through Betterment), the fair market value on the date of donation is used to calculate your itemized deduction. If you donate shares that you have owned for less than one year or shares that have gone down in value since the time of purchase (which you cannot do through Betterment), the cost basis or the fair market value, whichever is lower, will be used to calculate the deduction for which you are eligible. Again, Betterment aims to optimize tax deductions for charitable donations by only allowing our customers to donate appreciated investments held for over one year.