In the last VAT return, there were deviations from the expected/usual scope, which were not even mentioned. Only after two queries by e-mail had the situation become clear to me (by phone would be easier, but the office was unfortunately not available). Therefore, deviations from the usual should be explained in any case, e.g. in the cover letter. This saves frustration and queries.
Likewise, changes to the workflow should be explained in advance in a simple form.