The best approach her is to separate the tax from social welfare pension in your mind. The only people who issue PPSNs are Social Welfare Offices. Revenue stopped issuing them a few years ago. So, she should visit her local SW office adn ask to see teh Information officer. They will help her fill in form to get a number and also a Survivor's pension application can be completed. She will need her long version birth cerrt, marriage cert, death cert, photo ID (Passport or driving licence), adn proof of address (ESB, telephone bill). The pension claim can be processed even in the absence of tax affairs being sorted out.