There's no concept of nested tables in SQL Server. So whilst the code you've shown is correct for declaring a user-defined table (UDT) type, what you cannot do is then use that type as the declared type of a column in another table. All you can use UDTs for are for variable and parameter declarations1.
The more relational thing to do would be to just create this as a normal table with an additional column to act as a foreign key back to the Bills
table. An alternative, if you really do want to store the data "in-row" (although it'll actually be stored in separate pages physically) would be to declare the column as XML, and use the XML facilities instead to store and manipulate this data.
1 I've said something with certainty, so someone's bound to pop up and mention some third use case I've forgotten, but the general point stands.