Bills and law-making
How a Bill becomes law
A Bill is a proposal for a new law or a change to an existing law. Most public Bills pass through a series of stages in both the House of Commons and the House of Lords. Usually both Houses must agree the same text before Royal Assent turns the Bill into an Act of Parliament.
Short answer
A Bill normally has to complete its parliamentary stages in both Houses. The Houses can amend it, but they usually have to agree exactly the same final wording. Royal Assent then turns the Bill into an Act. The date on which individual provisions actually start operating can be later.
Interactive guide
Follow a Bill through Parliament
Choose which House the Bill starts in, then select any stage. You do not need to move through the timeline in order.
First Reading
The Bill is formally introduced in the House of Commons. This is normally a formality and there is no debate on the substance of the Bill.
Where can a Bill start?
A Bill can start in either the House of Commons or the House of Lords. If it completes the stages in its first House, it goes to the other House and is examined again.
Starting in the Commons
Many politically significant Government Bills start here. Bills mainly concerned with taxation or public money are among the categories that must begin in the Commons.
Starting in the Lords
Other Bills can begin in the Lords. Once the Lords has completed its stages, the Bill goes to the Commons and follows the Commons stages there.
The starting House is not enough
For the ordinary route, passing one House is not the end. The second House must also consider the Bill, and usually both must agree the same final text.
The five main stages in the first House
The names are the same in both Houses, although what happens within a stage can differ between the Commons and Lords.
First Reading
Formal introduction. The Bill is presented and published; there is normally no debate on its substance.
Second Reading
The House debates the Bill’s main purpose and general principles and decides whether it should continue.
Committee stage
Detailed scrutiny. Members can examine provisions and consider amendments, new clauses and other changes.
Report Stage
The Bill returns for further consideration. More amendments can be proposed and decided.
Third Reading
The House holds its final debate and decides whether to approve the Bill in the form it has reached.
Then the Bill goes to the other House
After Third Reading in the first House, an approved Bill goes to the other House. It broadly repeats the same five named stages there: First Reading, Second Reading, Committee, Report and Third Reading.
The two Houses do not conduct every stage in exactly the same way. For example, Commons committee scrutiny is often carried out by a Public Bill Committee, while Lords committee scrutiny is organised differently. At Third Reading, the Commons cannot make substantive amendments, whereas the Lords can make limited amendments in some circumstances.
After both Third Readings
Both Houses usually have to agree the same text
If the second House has amended the Bill, the first House considers those changes. It can agree, disagree or suggest alternatives. If the Houses still differ, the Bill can move back and forth between them until the wording is agreed. This is commonly called parliamentary “ping-pong”.
If agreement is not reached, a Bill can fall. There is an exceptional route under the Parliament Acts for certain Commons Bills, but that is not the ordinary process and will have its own guide.
Royal Assent: the Bill becomes an Act
Once the parliamentary stages are complete and the final text has been agreed, the Bill is ready for Royal Assent. Royal Assent is the Monarch’s formal agreement that turns the Bill into an Act of Parliament.
It is not an additional Commons or Lords vote on the policy. The parliamentary decisions have already been taken by this point.
When does the new law actually start?
Different Acts — and different sections within the same Act — can begin at different times. That is why “received Royal Assent” and “fully in force” are not always the same thing.
Immediately
Some provisions take effect on Royal Assent.
On a stated date
The Act can specify a future date or a period after Royal Assent.
By commencement order
An Act can give a minister power to bring particular provisions into force later by order.
A later guide will deal with commencement, territorial extent and implementation in more detail. This page includes only what is needed to understand the end of the Bill journey.
Some Bills do not follow this route exactly
The interactive timeline is the ordinary public-Bill route. These are some of the important reasons a real Bill may look different.
Common misunderstandings
Connect this to Project Open Gov
Follow a real Bill while it moves through Parliament
This guide explains the route. The Project Open Gov Bills Tracker shows real Bills, their current stage and recent movement. When a stage produces a recorded Commons division, the Votes feature and our vote guides explain what that individual decision means.
Continue learning
Learning area
How laws are made
Return to the landing page to explore delegated legislation, devolution and the other law-making routes.
Explore law-making →Votes and decisions
How bill stage votes work
Understand what MPs are deciding when divisions happen during the Commons stages of a Bill.
Read guide →Votes and decisions
How Lords amendment votes work
Understand Commons decisions on changes made by the Lords during consideration of amendments.
Read guide →Official sources
Use these sources to check the formal procedure and follow Bills through Parliament.