The IRD refused to confirm the maximum number of children each age group was liable for but gave total figures.
There were 252 18-year-olds liable for 262 children, 553 19-year-olds eligible for 608 children and 1080 20-year-olds liable for 1202 children. In total, 943 teenage fathers were liable to pay child support at the end of last year. Some were aged 15 and were already liable for two children.
The circumstances of the mothers of the 13 children are unknown, but any of them who are on the domestic purposes benefit are entitled to more than $293 a week, plus an accommodation supplement and other top-ups.
Benefits to support those 13 babies could cost the taxpayer more than $200,000 a year.