Margin Rates. Margin interest rates vary due to the base rate and the size of the debit balance. When setting base rates, TD Ameritrade considers indicators like commercially recognized interest rates, industry conditions related to credit, the availability of liquidity in the marketplace, and general market … Cash Management | TD Ameritrade Use cash management accounts to manage, move, and use your money easily . Flexible cash management provides you the freedom to access, spend, and manage your money the way you want - with a debit card and free ATM withdrawals, free check writing, and free online bill pay**. Manage your cash better with Online Cash Services from TD Ameritrade.