The topic chosen for this book is currently relevant given the increase in average life expectancy, which leads us to consider and problematise a new social reality: the ageing society. However, in parallel with the ageing of the population, a phenomenon has been developing: discrimination (in all its different guises) against the ageing population, discrimination based on age (and the possible resulting loss of operability). Discrimination is a contradiction in terms and must be prevented by applying and creating legal rules to protect this risk group, which in the future will be the majority and needs special care and legal rules suited to its special condition/vulnerability. This book is intended as a small contribution in this area in terms of tax law and is aimed at anyone with an interest in the legal problems of ageing and related tax aspects.