Backdated deregistration after departure from Netherlands

Question

What is the best option to re-register if somebody, unfortunately, forgot to do that while leaving NL for a month or so ago? 1) Online - which do not allow backdated deregistering 2) Send the filled-in & signed deregistration form in international post to municipality with backdated

Answer 1

I found online registration to be better option, as it guranteed the date on which form gets submitted to bet the de-reg date. One can get back to the munciple authority later, to request getting it back dated.