The CBS emigration figures take account of so-called administrative corrections, i.e. cumulative registrations in and removals from the population register. Removals concern persons who are removed from the municipal register after it has been confirmed that their place of residence is unknown, they cannot be reached, and they are likely no longer a resident of that municipality. Such persons have presumably moved abroad and failed to deregister, e.g. in cases where they were not expecting an extended stay abroad, they were not familiar with the regulations, or did not give it any priority (for example a foreign student who graduates here and returns home). Should they return to the Netherlands or turn out to have been staying in the country, they can then register as residents again. Especially those data concerning removals usually reach CBS at a later stage.
As a result, the number of removals over the most recent period is expected to turn out higher and the number of emigrants is expected to turn out lower in the final calculations. This means net migration will actually also turn out lower.