An impartial voting guide for the EU referendum will drop through the letterboxes of 28 million households across the UK from 16 May.
The eight-page booklet gives advice on who can vote, how to register and a page on each of the lead campaigns.
It is part of a £6.4m awareness campaign organised by the Electoral Commission, which includes a TV advert.
People not on the electoral register have until 7 June to apply for a vote in 23 June's referendum.
Around 7.5 million people in Britain are not registered to vote - and a recent survey by the commission suggested that a fifth of survey respondents were either not registered or were unsure if they were registered to vote.
'Consider a proxy'
The commission says its campaign - "You can't miss it" - is designed to "cut through the noise" that everyone will be hearing about the EU referendum.
It comes a month after the government spent £9m distributing a 16-page pro-EU membership leaflet to 27 million UK homes - a move which drew heavy criticism from Leave campaigners.
Alex Robertson, the Electoral Commission's director of communications, says the commission's booklet "gives everyone the information they need".
"This is an historic event and we don't want anyone to miss out," he said.
"A lot of people won't have voted in a referendum before - or will be unsure what the question is.
"If you aren't already registered to vote, then make sure you do it by the 7 June deadline or you'll miss out on the referendum. It's easy and only takes a few minutes online. Tens of thousands of people are doing it every day."
The commission is also advising voters to think about where they will be on polling day. Anyone who is likely to be away on Thursday, 23 June should consider applying to vote by post or via a proxy - a trusted person permitted to vote on their behalf.
Glastonbury festival, which clashes with polling day, is encouraging the expected 135,000 or more attendees to register for a postal vote so that they don't miss out. The Electoral Commission has confirmed that there will be no polling stations on the festival site.
Electoral Commission advertising will run until polling day and appear across TV, radio, video on demand services, billboards, digital and social media.
Bilingual versions of the booklet - which cost £2.4m to produce and deliver - will be delivered to households in Wales.
Nearly 140,000 people registered to vote in the final through weeks before the Scottish referendum in September 2014. Over 11,000 applied to register after the deadline - and missed out as a result.