When to use the Retirement income feature, while reserving money to leave a legacy?

Our advice model does not currently account for leaving assets to your heirs, but we plan to add this in the future. For now, you can use the graphing capabilities on the Advice tab to estimate how much will be left at the end of the horizon given the withdrawals you enter.

That being said, you can also add beneficiaries to any of your Betterment accounts, which would supersede any will or trust.