I am a seller from another EU country (Portugal, France, Germany, Italy, Netherlands…). Do I need a Spanish EPR representative?

Yes, if you sell packaged goods directly to end users in Spain. MITECO's note works exactly this case: a Portuguese company selling online to Spanish consumers is the producer in Spain of its sales and shipping packaging, and must appoint a Spanish authorised representative. Your registration in your own country covers only that country. Using OSS for VAT does not make you established in Spain, and you will still need a Spanish NIF starting with N for the registration. If you sell only to Spanish businesses that resell, the Spanish buyer is the producer instead. RRegulation (EU) 2025/40 (PPW+3