This study explores the moral, affective, and institutional foundations of social capital in Spain’s fiscal context. Using microdata from the Centro de Investigaciones Sociológicas (2022), an exploratory factor analysis (EFA) identified six latent dimensions—Fiscal moral demand, Public-service satisfaction, Subjective well-being, Perceived tax burden, Social mobility, and Civic norms—together with two standardized single-indicator variables capturing Interpersonal trust and Ideological self-placement. All variables were standardized so that higher scores represent greater intensity of the construct. The factorial structure remained consistent across extraction methods (ML, PAF, ULS) and under both complete-case and imputed data treatments, yielding a stable and replicable measurement of attitudinal dimensions of civic and fiscal behavior. Two-way ANOVAs examined differences by gender and municipality size. Gender effects were modest yet theoretically meaningful: women reported slightly higher ethical commitment, satisfaction with public services, and well-being, whereas men perceived greater fiscal pressure and positioned themselves marginally further to the right on the ideological scale. Territorial variation was limited but coherent—residents of medium and large cities expressed stricter moral expectations and marginally higher interpersonal trust, though the effect sizes were trivial. A single significant interaction in Interpersonal trust revealed that women in larger municipalities showed higher confidence than men, while no gender gap appeared in smaller localities. Overall, these results indicate a qualified stability of civic orientations across demographic contexts. Methodologically, the study provides statistically robust evidence that social capital can be consistently assessed as a multidimensional attitudinal construct through convergent factor extraction, reliability diagnostics, and inferential validation. Substantively, the results indicate that Spain’s civic culture combines strong moral commitment with moderate distributive skepticism. Policies promoting transparency, fairness, and civic education could further strengthen the moral and affective foundations of fiscal cooperation and social cohesion.