The Act allows British citizens who are resident outside the United Kingdom to qualify as "overseas electors" in the constituency for which they were last registered for a period of five years after they have left (this was subsequently changed to 20 years and is now 15 years).
Under the Act, British residents living abroad can be designated as "overseas electors" within their previous electoral district if they were previously registered in that area for a minimum of five years following their departure. This period was later adjusted to 20 years and is now 15 years.