Parents who have not received a claim form for child benefit by today should contact the Department of Social Care.
Department Minister Chris Robertshaw has warned of a potential backlog if the forms aren't completed and returned quickly.
The existing child benefit scheme ends on April 6 and will be means-tested from April 7.
Mr Robertshaw said he was 'surprised' by the lack of returns after the first batch was issued. All parents have now been written to.
He said: 'If people do not get them by Tuesday, please get in touch. I beg people to get these forms back to us. Please do not think we can deal with a rush right at the end. Those with a household income of less than £60,000 should not assume they have an automatic right to child benefit.'
The letters state that families with an assessed income of £60,000 or less will receive the full rate for all their children. Families earning up to £90,000 will receive a reduced rate, while families in an income bracket above £90,000 will not receive any child benefit.
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