It is considered advisable that, as much as possible, the first reference year for the data transmission of ISCO-08 data is the same in all statistical domains concerned, in line with the next round of Census, which will have 2011 as reference year.
Peetakse soovitavaks, et võimaluse korral määratakse ISCO-08 andmete edastamise esimeseks vaatlusaastaks sama aasta, mis muude statistikavaldkondade puhul, kooskõlas järgmise rahvaloendusega, mille vaatlusaasta on 2011.