How a bill becomes law in the UK

The sequence, stage by stage

First reading is formal notice: the bill is introduced and printed, with no debate. Second reading is the first debate and vote, on the principle of the bill rather than its detail. Committee stage examines the bill line by line and is where most amendments are made. Report stage lets the whole House review the amended bill and change it further. Third reading is the final vote in that House.

The bill then goes through all five stages again in the second House. A bill can start in either House, though bills mainly about taxation or spending always start in the Commons.

Agreeing a single text

If the second House amends the bill, the first House must consider those amendments, and the two Houses exchange proposals until they agree, the process known as ping pong. The Lords generally sees its job as asking the Commons to think again rather than blocking it, and behind the convention sits the Parliament Acts, under which most Commons bills can ultimately pass without the Lords’ consent after a year’s delay.

When both Houses have agreed the same text, the bill receives Royal Assent and becomes an Act of Parliament. In modern practice assent is a formality, last refused in 1708.

How long it takes

There is no fixed timetable. A typical government bill takes several months to a year; an emergency bill can pass every stage in both Houses in days; a contested bill can take well over a year. Bills that have not finished their passage when a parliamentary session ends normally fall, unless carried over to the next session, and every bill still in progress falls when Parliament is dissolved for a general election.

Becoming an Act is also not the same as being in force. Many Acts commence in stages, with ministers switching provisions on by regulation over months or years.

How to track a bill

Every bill’s stage history is published as it happens. Our free bill tracker lists every bill currently before Parliament with its stage, sponsor and latest activity, and each stage in this guide links to a fuller page on what that stage involves, with the bills at that stage right now.

Related guides

• What happens at first reading of a bill
• What happens at committee stage of a bill
• What happens at Royal Assent
• What happens to a bill when a session ends