capturing radio button values for nested object

I have a user object and an account object. User has one account
object. In the signup.rhtml I have a radio button that has three
options for the membership (yearly, monthly and sample). How do I
populate the account model when the user submits the form?
Is the following syntax correct?

<%= radio_button("user[account]", "membership", "Yearly") %>
Yearly<br>
<%= radio_button("user[account]", "membership", "Monthly") %>
Monthly<br>
<%= radio_button("user[account]", "membership", "Sample") %>
Sample<br>

TIA