Can the Tax Office issue an assessment when I didn't file a return?
Yes — a "ex officio" assessment based on estimate. Often well above reality. File the return AND object = right to correction.
On failure to file a required return, the Tax Office may issue an ex officio assessment under AWR art. 11(2). Often based on a generous estimate + filing penalty (max €5,514 per offence). What to do: (1) file the return belatedly — this right persists after the assessment; (2) object within 6 weeks of date stamp, citing your now-filed return; (3) request reduction of the assessment to actually-owed. The inspector must revise an ex officio assessment on receiving correct figures (AWR art. 65). Pro tip: submit return + objection together, with copy to the Collector to halt collection.