I was wondering if I need to capitalize it because my teacher highlighted it but without giving a reason.
When referring to a specific bill, the word "bill" has to be capitalized, i.e. ( Acts Interpretation Amendment Bill 2011).
However, when referring to any bills like for example:
The bill would not be needed to be capitalized.
Note how the Hon. Ian MacDonald moved for "these bills" to be read a second time.
The word "bill" should not be capitalized even in the following sentence:
Senator, please support amending Water Code bill.