This chapter explores the productive influence of fiscal accounting culture on the literature of vernacular penitential instruction. I define ‘vernacular penitential instruction’ as pastoral texts that taught the laity the basics of penance and confession along with fundamental doctrinal tenets. The fourteenth to early fifteenth centuries were the golden age of vernacular penitential pedagogy that witnessed both the translation of numerous Latin penitential and the creation of new vernacularized material. This period also saw the rise of accounting literacy and technology as European society became increasingly commercialized. Beginning with an examination of medieval accounting technologies, I show that tools of accounting were used to facilitate a collaborative accounting network that generated an ethic of collective responsibility. From there, I illuminate how writers of penitential instruction drew from this collaborative accounting culture to teach confession as a similarly collaborative process that tied sinners to each other in chains of relational accountability. While many have observed, following Foucault, that confession is primarily an expression of interior subjectivity, this pedagogical overlap between accounting and penance demonstrates that confession can also be an important communal practice that fostered layers of new relational responsibilities among confessors, penitents, and their fellow neighbors.