A top election official apologised tonight to voters who were accidentally charged over £5 (€5.75) to receive their polling cards.
Chief Electoral Officer Douglas Bain promised to refund the people affected in the Shankill area of Belfast.
It emerged that officials forgot to pay the postage on replacement polling cards issued after an earlier mistake.
In other areas there were complaints that polling cards had not arrived at all - but the Electoral Commission tonight reminded the public that they do not need a polling card to cast their vote tomorrow.
The Head of the Electoral Commission’s office in the North, Seamus Magee, reminded voters, however, to bring the correct photographic ID when they go to the polls.
“As long as you are registered, you do not need to bring a polling card but do bring your ID or you will not be able to vote,” he said.
“If you’re not sure if you are on the electoral register, or of the location of your polling station, you should telephone our helpline on 0800 0323 700.”
In order to vote, you must bring one of the following forms of photographic ID:
:: A UK, Irish or EU passport
:: A UK driving licence
:: A Translink Senior Smartpass, 60+ Smartpass, Blind Persons Smartpass or War Disabled Smartpass
:: An electoral identity card
The eligible electorate in the North is 1,141,979, an increase on the 2004 figure of 1,072,669.
At the last European Poll 51.72 % of people eligible to vote did so, which represented 554,744 votes.
The North has seven candidates fighting for the region’s three European Parliamentary seats.
They are Stephen Agnew of the Green Party, Jim Allister of Traditional Unionist Voice, Bairbre de Brún of Sinn Féin, Diane Dodds of the DUP, Alban Maginness of the SDLP, Jim Nicholson of the Ulster Conservatives and Unionists, and Ian Parsley of the Alliance Party.
The votes cast will be validated at the King’s Hall in Belfast on Sunday before counting starts on Monday morning.
The first results are expected by mid afternoon on Monday.
The Electoral Commission is urging anyone with any questions to call the helpline on 0800 0323 700 or log on to www.aboutmyvote.com.
The Electoral Commission has reminded eligible voters to make sure they understand the voting system.
“Votes are cast by putting the number ’1’ against the voter’s preferred candidate; a ’2’ in the box beside their next favourite and so on until they no longer wish to express a preference,” said the Commission.
“You can vote for as many or as few candidates as you wish. People who complete the ballot paper incorrectly spoil their vote, so it is important to remember that if you are eligible to vote and go along to the polling station you must follow this method.”