Quote: NPIP laws as far as i know vary from state to state. in Ohio we have to be members of NPIP to ship eggs and chicks.
all i can explain is Ohio's methods, i hope it answers your questions. it is a club for lack of better description. you pay a $50 a year membership and they test a percentage of your flock for avian flu, typhoid, and pullorum. if your flock tests clean they give you paperwork to send with sold chickens; showing that you've tested clean, your number, and a list of what you bought. a copy of this goes to the department of agriculture too. it is simply to help stop the spread of poultry illnesses, and to aid in tracing where your chickens are sold in case you do have a problem. If there is a problem illness in your neighborhood, they will notify you; so you can take appropriate measures.
for me, becoming a member of NPIP was simple, probably the hardest part was deciding to fork over the $50. now that i am a member i, will remain a member as long as i own my flock. It is my way of reassuring people who buy from me that my birds are tested for illness. once you become a member, they ask that you buy from other members of NPIP; if you buy from non-members, they ask that you have the chickens tested before you sell any from them.
they also list the members along with what they have, so if your looking for something specific; you can find someone who has it.
in Ohio it's a yearly membership.