It depends on why your mother transferred the money to your account. If it's a gift, you do not pay tax on it, and you don't even enter it in your tax return. However, your mother must file a gift tax return, Form 709, which applies the gift to her lifetime exclusion. She will not have to pay any gift tax unless she has exceeded the lifetime exclusion, but she has to file the return.
You do have to pay tax on any income that you earn on the money after it is in your account.
If the money is something other than an unrestricted gift, post more details.
