The UK government opened a formal public consultation on 18 June 2026 on plans for a third runway at Heathrow airport. This is the official legal process that will decide whether the project can go ahead.

Think of it like this: before a major building project gets permission, the government has to set out the rules it will use to judge the application. That document of rules is called the National Policy Statement. This consultation is the process where the government listens to what the public, local councils, airlines, environmental groups, and others think about those rules — before they become law.

The government has set three main conditions for expansion. First, it must be cost-effective. Second, it must not burden air passengers with extra costs. Third, and most important, it must not cost taxpayers anything. Instead, the airport and investors must pay for it themselves.

There is also a new requirement: Heathrow must show clearly how the project will create jobs and benefit the wider economy. The government is saying it is not enough to claim the project will be good for the economy overall — Heathrow must prove where the jobs will go and who will benefit.

Heathrow has been seeking a third runway for a long time. The government first backed the idea in October 2016. Since then, there have been legal battles, the pandemic disrupted passenger forecasts, and the plans have changed multiple times. This new consultation is a fresh process, but it carries real weight: it is the first step in the formal legal procedure that could actually lead to building.

Members of the public can find the consultation documents on heathrow.com/expansion. The consultation period allows local councils, airlines, environmental groups, and people affected by the airport to send in their views on the draft plan. Once the consultation ends, parliament has to vote to approve the rules. This matters because some MPs represent areas under the flight paths.

The rule about no cost to taxpayers is important to understand. It means the airport cannot ask the government for money, either directly or through borrowing that the government guarantees. It also means the airport cannot use a system where passengers' fares go up now to pay for building costs that would happen later. Investors and the Civil Aviation Authority — the regulator — will need to work out whether this is possible and how expensive it will be.

The jobs requirement is demanding too. Heathrow will not just have to say employment will grow — it will have to prove it, with monitoring plans in place. That is harder than what the project has had to do before. It will affect deals the airport makes with local councils about jobs and other benefits.

One thing this consultation does not answer is when all this will happen. Getting approval for the rules, the airport submitting its formal application, and then examining that application all take time. Nobody involved is quite sure how long yet.