Bills and Acts
Bills are written documents that can be amended by Parliament. A bill may be reprinted more than once during its progress through either House, to incorporate changes that have been made. This means that differing versions of a bill may have existed before its final text is agreed.
A bill becomes an Act of Parliament once the same text is approved by the House of Commons and the House of Lords, and it receives Royal Assent.
After a bill becomes an Act, it is the responsibility of the appropriate government department to publish, implement and enforce it. The text of an Act does not normally change unless Parliament passes a later bill that adds to, removes or replaces words in its text.
Numbering of Bills and Acts
Bills are numbered sequentially, in the order they are presented, starting at Bill No.1 in each House at the start of each parliamentary session. A new number is assigned to a bill each time it is reprinted. A Commons bill that progresses to the Lords is reprinted as a House of Lords bill and is assigned the next sequential number in that House, and vice versa.
Acts of Parliament are given a permanent chapter number when they are passed into law. Chapter numbers are allocated sequentially within each calendar year, beginning at Chapter [or Cap] 1 from the start of January each year. This number does not change making it a key identifier, when combined with the year, for an Act.
Access to current bills and Acts
Parliamentary bills from 2006-07 onwards are available on the bills pages of the Parliament website: Bills before Parliament
Acts of Parliament from 1988 onwards (and earlier Acts that are still in force) are available on the government's Legislation website: Legislation - GOV.UK
Access to earlier bills and Acts
Earlier Commons and Lords bills, and original versions of Acts from 1497 onwards, are held in hardcopy by the National Archives as part of Parliament's archive collection. Information about arranging access to, or ordering copies from, this collection is given on the National Archives website.
In addition, House of Commons bills from 1715 to 2015 - and House of Lords Bills from the 19th Century - are digitised and available via Proquest UK Parliamentary Papers, a subscription service available at many university libraries and large reference libraries, including onsite at the National Archives.
Further guidance on tracing Acts of Parliament and any changes that have later been made to them can be found on the Legislation website at: Help with Legislation or by using their Research Tools.