LONDON — Some British citizens planning to travel abroad already have a tangible sign of what life will look like once the country is no longer a member of the European Union: new passports missing “European Union” on the front cover.

Last month, even as lawmakers wrestled over the principal terms of the withdrawal process known as Brexit, the Home Office said that the design of new passports would change after March 29, the initial date set for Britain’s departure.

For a while, both the old and new designs will be made and both are valid for travel, the Home Office said, adding, “You will not be able to choose whether you get a passport that includes the words European Union or a passport that does not.”

While Brexit itself has been delayed — the original departure deadline was extended to April 12, and Prime Minister Theresa May has asked Brussels for a further postponement — the passport changes have moved forward as planned.