What documents to close when leaving Hungary?

Hi,
Im an expat, and i was living in Hungary until september. After a really lovely time there i had to say bye.
There are few documents to close, and i wonder if someone had the same experience,
About health public insurance card, i was informed that i should fill in form 18T10011-B. Also i should inform to hungarian authorites the new health insurance number from my new country. Than is possible to finish and send this information by post.
About tax number, i was inform that is not necessary to close, not sure here, i need some help to understand better.
About address card, is it really necessary to close?
We are in 3. Mysefl, wife and my son (7 years), all EU citizens
We dont have plans to go back to hungary unfortunatelly

I appreciate some comments,
Köszönöm!

When I left Hungary - the 1st time many years ago - I tried to deregister myself with quite a few organisations and was told there was no forms or procedure to say you are going.  So I just basically left.  Interestingly when I came back years later, my tax number was the exactly the same and no-one asked me anything about why I was gone for years.