NBER Working Papers by Claus Kreiner

This paper analyzes a randomized tax enforcement experiment in Denmark. In the base year, a stratified and representative sample of over 40,000 individual income tax filers was selected for the experiment. Half of the tax filers were randomly selected to be thoroughly audited, while the rest were deliberately not audited. The following year, "threat-of-audit" letters were randomly assigned and sent to tax filers in both groups. Using comprehensive administrative tax data, we present four main findings. First, we find that the tax evasion rate is very small (0.3%) for income subject to third-party reporting, but substantial (37%) for self-reported income. Since 95% of all income is third-party reported, the overall evasion rate is very modest. Second, using bunching evidence around large an...

This paper presents a simple agency model to explain why third-party income reporting by employers dramatically improves income tax enforcement. Modern firms have a large number of employees and carry out complex production tasks, which requires the use of accurate business records. Because such records are widely used within the firm, any single employee can denounce collusive tax cheating between employees and the employer by revealing the true records to the government. We show that, if a firm is large enough, such whistleblowing threats will make tax enforcement successful even with low penalties and low audit rates. Embedding this agency model into the standard Allingham-Sandmo tax evasion model, we show that third-party reporting improves tax enforcement if the government disallows s...

This paper analyzes the optimal income tax treatment of couples. Each couple is modelled as a single rational economic agent supplying labor along two dimensions: primary and secondary earnings. We consider fully general joint income tax systems. Separate taxation is never optimal if social welfare depends on total couple incomes. In a model where secondary earners make only a binary work decision (work or not work), we demonstrate that the marginal tax rate of the primary earner is lower when the spouse works. As a result, the tax distortion on the secondary earner decreases with the earnings of the primary earner and actually vanishes to zero asymptotically. Such negative jointness is optimal because redistribution from two-earner toward one-earner couples is more valuable when primary e...