The theme of authority and consent is among those at the centre of the attention and reflection as much of the aficionados of administrative law as the devotees of tax law. Reconstructive similarities and differences of great interest emerge regarding the various problems proper to the two different areas, which make the continuation of the comparison desirable, which, including in the perspective of a hoped-for more general closer relationship of the two disciplinary ambits, could well be extended to include other topics. In this perspective, it may be opportune to verify whether a paradigmatic feature of tax law - what Law No. 218 of 1997 describes as 'assessment with assent' - is conceptually traceable to the figure of the administrative agreements pursuant to Art. 11 of Law No. 241 of 1990 (or 'LPA') on administrative proceedings.