The Royal British Legion and the UK Government are encouraging veterans to get in touch early so they can mark the poignant occasion "according to their wishes".
Members of the public are also being asked to spread the message and help any D-Day veterans in accessing a purpose-built website or contacting the Legion.
The Normandy Landings, commonly referred to as D-Day, began on June 6 in 1944 when allied forces launched a combined naval, air and land assault on Nazi-occupied Europe.
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The Legion and the Government, along with organisations including the Commonwealth War Graves Commission, the Normandy Memorial Trust and the Spirit of Normandy Trust are planning commemorations to mark D-Day 75, both in France and across the UK.
Defence Secretary Gavin Williamson said: "The Normandy Landings were the vital springboard to the liberation of Europe and the end of the Second World War.
"The breath-taking bravery and ingenuity shown during those days still echo through today's armed forces.
"At D-Day 75 the eyes of the world will be on these men once more. To enable us to do them justice it's important we find as many veterans as possible and let them know how to participate.
"We will never forget the debt we owe for the peace and freedom we now enjoy on this continent."
Memorial services are set to take place in Normandy, the South Coast, the National Memorial Arboretum, Scotland, Wales and Northern Ireland.
Veterans and their families that register on the D-Day 75 website will be kept updated as plans are confirmed and more details are released.
Charles Byrne, director general of the Royal British Legion, said: "D-Day 75 is only a year away and significant plans are already afoot.
"We want to ensure that every veteran can mark this incredibly important occasion exactly where and how they want.
"To ensure the utmost care and attention can be given to the ex-servicemen, now in their nineties, the Legion and its partners need the public's help to make sure as many come forward as soon as possible.
"If you are a friend or family member of a D-Day veteran, please help them to get in touch with us."
The website is www.britishlegion.org.uk/dday75.