Family Homeschool Number
The number will have, currently, 5 digits (older ones had 4), followed by a -1 for the first child exempt, a -2 for the second child and so on. For example, if the Smith family are homeschooling 3 exempt students, their family numbers might be 12345-1, 12345-2 and 12345-3.
You will seldom need to use this number, but it will come in handy if corresponding with the Ministry about anything to do with your family exemptions. So keep a record of it in a safe place.
National Student Numbers
If at any time you wish to enrol your child in a program which has credits or funding attached to it, then you will need their NSN number. You will also need it to complete an NZQA registration, which is also needed for earned credits to be recorded on the Framework, and to access those records.
You will also need an NSN to check eligibility for Fees Free via the Fees Free website.
It is mostly families of older students who need their NSN. Until now, finding out your student's NSN has required contacting the Ministry of Education and requesting it* - an often frustrating process. Last year at our meeting with the Ministry, in my role as Government Liaison for the National Council of Home Educators of NZ (NCHENZ), I requested that student NSNs be made easily accessible by including them with future exemption certificates and also adding them to the six monthly declarations. The Ministry agreed, and as of the current round of declarations (March 2020), these have been added.**
Now on your declarations you should see a line for each student which states:
Family homeschooling number, student's full name, students NSN.
Just one more reason to keep a copy of your declaration and not just shove it back in the post and return it. :-)