Purpose: Tax compliance of natural persons, especially business owners and small businesses, requires a distinct approach from that of legal entities due to cognitive, time, and information constraints, as well as exposure to the complexities of the tax system. This study aims to provide a stage-based model for improving the tax compliance of natural persons based on nudge theory and the six principles of choice architecture (NUDGES) in Iran’s tax system. In this model, tax compliance is conceptualized as a four-stage process including registration and identification, bookkeeping and document maintenance, tax return filing, and tax payment. At each stage, six behavioral components—defaults, feedback, incentives, error mapping, choice mapping, and structuring complex choices—are examined.
Methodology: In terms of purpose, the research is applied; in terms of approach, it is quantitative; in terms of data collection, it is survey-based; and in terms of time, it is cross-sectional. The research design is non-experimental, and data were collected through a researcher-made questionnaire with 60 items. The statistical sample consisted of 390 natural-person taxpayers, tax advisors, auditors, tax affairs experts, and individuals with a background in taxation, accounting, and financial management, selected through purposive sampling. Content validity was confirmed using CVR and CVI, reliability using Cronbach’s alpha (0.965), and factor structure using exploratory factor analysis/principal component analysis, KMO (0.885), and Bartlett’s test. In addition to descriptive statistics, one-sample t-test and Friedman test were used to analyze the data.
Findings: The results showed that applying nudge theory can significantly improve the tax compliance of natural persons at all four stages (p < 0.01). Overall, the priority of nudge components was as follows: defaults (3.76), choice mapping (3.57), feedback (3.56), structuring complex choices (3.43), error mapping (3.41), and incentives (3.35). Priorities also differed across stages: at the registration and identification stage, “defaults” and “error mapping”; at the bookkeeping and document maintenance stage, “feedback” and “incentives”; at the tax return filing stage, “structuring complex choices” and “choice mapping”; and at the payment stage, “feedback” and “defaults” had the highest priority and impact.
Conclusion: The final model of the study was designed based on the matrix “compliance stage × taxpayer type × nudge component” and shows that behavioral interventions should be designed and implemented in accordance with the compliance stage and the specific characteristics of natural persons. Accordingly, four policy rules are proposed: automation and defaults in registration, continuous feedback in bookkeeping, reducing cognitive load in tax returns, and reminders and clarification of consequences in payment. The conclusion emphasizes that improving compliance is possible not by replacing deterrence with nudges, but by intelligently designing the decision environment at each stage of the compliance cycle, and field testing of the model in future research is necessary. By presenting a stage-based and differentiated model, this study fills the existing research gap regarding the application of nudge theory in Iran’s tax system and provides practical policy recommendations for the Iranian National Tax Administration.