Objective: To identify cognitive predictors of declining financial capacity (FC) in persons with mild cognitive impairment (MCI). Methods: Participants were 66 cognitively normal older adults and 49 persons with MCI who completed neuropsychological testing and a performance measure of financial capacity (Financial Capacity Instrument; FCI) at baseline and two-year follow-up. We calculated two-year change scores for neuropsychological tests and FCI total score. We examined bivariate correlations between demographic/clinical variables and FCI change score, and between neuropsychological and FCI change scores. The five strongest bivariate correlates were entered into a linear regression analysis to identify longitudinal predictors of financial decline within group. Results: Persons with MCI showed significant decline on the FCI and most cognitive variables, while controls demonstrated relatively stable performance. For persons with MCI, education correlated with FCI change score. The top four cognitive variable-FCI change score correlations were written arithmetic, confrontation naming, immediate visual memory, and visual attention. In the regression model, written arithmetic was the primary predictor and visual memory and visual attention were secondary predictors of two-year FCI change scores. Conclusion: Semantic arithmetic knowledge, and to a lesser extent visual memory and attention, are key longitudinal cognitive predictors of financial skill decline in individuals with MCI. Clinical Implications: Clinicians should consider neurocognitive abilities of written arithmetic, visual memory, and processing speed in their assessments of financial capacity in person with MCI.