Letter asks to confirm IBAN for "refund" — real?
99% scam. Tax Office uses known IBAN — changes only via MijnBelastingdienst portal. Phone or email confirmation always suspicious.
Tax Office has your IBAN via bank linking (auto-shared) or your MijnBelastingdienst settings. Refunds go to known IBAN. RED FLAGS: (1) Email/letter asks IBAN confirmation for "refund" or "verification"; (2) Email link to fake site with DigiD login; (3) Caller asks new IBAN with threat or reward; (4) "Improved account" or "new admin" — scammer pretext. LEGITIMATE: IBAN change via MijnBelastingdienst portal after DigiD login (initiated by you). VERIFY on doubt: log directly into MijnBelastingdienst (type BELASTINGDIENST.NL directly, not email link); check actual refund or correspondence pending. Unknown: scam. Already complied and payment to wrong IBAN? Immediately: (a) call bank for chargeback (often back within 8 hours); (b) call BelastingTelefoon 0800-0543; (c) file police + Fraudehelpdesk report.