The new Northern Ireland Electoral Register is down more than 28,000 electors compared to the one used in last year's Assembly elections.
Just over one million people have registered
It is being published on Monday and will be used for all this year's elections.
Just over one million people have registered.
Northern Ireland's chief electoral officer, Denis Stanley, said there was still time to ensure people have a vote in June's European Elections.
"We are very anxious to target people, such as young people, who perhaps haven't been on the register before - coming up to 18 - to get them on.
Those with learning disabilities
Residents in poorer areas
"We are also keen to look to people who perhaps come from a disadvantaged background, or people who don't have English as their first language or have literacy problems.
"We want to look at all of those people and encourage anyone who should be on the register to get their names down as quickly as possible."
A report in December last year said measures to combat voting fraud in Northern Ireland had a negative impact on young people and those in poorer areas.
The need to register every year was brought in by the Electoral Fraud Act 2002.
In the past, one form was given to every household, but now everyone has to register individually.
The Electoral Commission said this measure tended to have an adverse impact on disadvantaged, marginalised and hard to reach groups.
It meant young people, students, people with learning disabilities and those living in poorer areas were less likely to register, according to the government-appointed watchdog.
The report also called for a review of the special hearings procedure for those who want to be added to the electoral register.
It said the practice was unique to Northern Ireland.
Thousands of people who applied to get their names added to the voting register were asked to attend such hearings.
The commission says less than half of them showed up, suggesting that they were put off by the hearings' "semi-judicial nature".