Kidnappers are among the serious violent criminals whose benefits police will be able to block.
Under sweeping benefit reforms to take effect next month, police will work closely with the Ministries of Social Development and Justice to match data on beneficiaries in trouble with the law.
The Ministry of Social Development will stop benefits to people with outstanding arrest warrants who do not turn themselves in after 38 days, and police will be able to tell officials to cut benefits to serious offenders.
A spokeswoman for Social Development Minister Paula Bennett said a person would be considered a danger to the public if they had committed serious, violent crimes and were on the run from police.
"If it was a kidnapping that's in progress and they haven't been able to track down the person - those kinds of things will be considered exceptional circumstances."