Can the Tax Office require DigiD for all communication?
No — for people without DigiD, written (paper) communication remains available. Statutorily guaranteed. On refusal: object + Ombudsman.
The Tax Office may make digital communication the default, but not the only option. Under Awb art. 2:14 + Electronic Administrative Traffic Decree, a citizen who can't/won't use DigiD has the right to paper equivalent. For people who can't do digital (elderly, disabled, non-Dutch): request "paper delivery" via Tax Office form (free). Renew this per assessment. Refusal complaint: (1) internal Tax Office procedure; (2) National Ombudsman — has been critical here repeatedly; (3) Persistent refusal: administrative court on human rights (ECHR art. 6 — access to remedies). Key: Tax Office sends no SMS or email with pay links (see sms-belastingdienst-scam). Official digital communication is EXCLUSIVELY via MijnBelastingdienst portal after DigiD login. Other "mailings" are scams.