David Cameron will warn young people they would be the hardest hit if Britain leaves the European Union as he seeks to bolster support for the "remain" camp.
The Prime Minister will issue the stark caution at the launch of a drive to recruit younger voters - who are generally less likely to vote than more anti-EU older generations.
His intervention - at a question and answer session in Devon - comes as he faced criticism from pro-Brexit campaigners for spending £9.3 million of taxpayers' money on a pro-EU publicity drive.
The Government said it was sending a leaflet to every UK household setting out the case for staying in - backed by an online campaign - because it was "crucial that the public have clear and accessible information".
Downing Street said the move was a response to polling which showed 85% of the public wanted more information from the Government to help them make an informed choice on June 23.
But opponents said it was a waste of public money that breached ministers' assurances that the Government would not seek to play a significant role in the campaign and unfairly skewed the debate.
Ukip leader Nigel Farage said the document was "jammed full of lies and inaccuracies" and was legally questionable and morally wrong and London Mayor Boris Johnson branded it "very biased and hysterical".
Speaking at the formal launch of the Brighter Future IN campaign, Mr Cameron will point to evidence that youth unemployment rises fastest in the sort of economic slump the "remain" camp say would hit Britain if it left the EU.
"I want to speak very directly to the young people of Britain about this referendum," he will say.
"The facts are these. Young people are less likely to vote than older people. Yet you're the ones that are going to be most affected by the outcome - more than any other vote in your lifetime.
"The jobs you'll do, the prices you'll pay, the chances you'll get to work, study and travel - so many of your future opportunities are connected to whether Britain is in or out of Europe.
"And remember: it's widely accepted there would be an economic shock if we left. Who gets hit hardest by those shocks? Young people.
"So get out there. Register. Vote. Tell your parents, grandparents, friends and colleagues: this referendum will really help determine whether your generation is stronger, safer and better off."
The leaflet is costing £458,500 to create, with £5,947,436 being spent printing and delivering it to over 27 million homes across the UK in two waves - to the fury of "leave" campaigners.
Another £2,894,064 will go on producing the website and promoting it via social media and other online platforms - a total cost of around 34p per household.
The leaflet, titled "Why the Government believes that voting to remain in the European Union is the best decision for the UK", will start to arrive through letterboxes in England next week - before "purdah" restrictions come into force ahead of May's local elections - and in Scotland, Wales and Northern Ireland from the week after the May 5 elections.
The leaflet tells voters that leaving the EU would "reduce investment and cost jobs", could push up food prices and damage living standards and that there would be "no guarantees" that flights to European destinations would rise, mobile phone roaming charges go up and access to free or cheaper healthcare on holiday come to an end.
The cost of the promotional push was greater than the £7 million each the formal "leave" and "remain" camps will be allowed to spend by law in total during the last 10 weeks of the campaign, Vote Leave complained.
Mr Johnson - one of several leading Tories to have broken ranks to back Brexit - said it was "crazy to use quite so much taxpayers' money on stuff that is basically intended to scare people and to stampede people in one direction".
"What we want is a proper, informed debate and if you are going to use taxpayers' money you should allow people to put the other side of the case as well".
Mr Farage said: "This Government scam confirms my view that this referendum will be defined by the battle of the people versus the political class.
"Furthermore, the document is jammed full of lies and inaccuracies including the claim that we currently control our borders. We don't. It is outrageous to suggest otherwise."
Tory MP Peter Bone, co-founder of the Grassroots Out campaign, said it was "immoral, undemocratic and against what the Government has promised".
And Liz Bilney, chief executive of the Leave.EU campaign, said it was "putting the legitimacy of the final result at great risk".