I leverage the staggered rollout of VAT in Pakistan to document the role of withholding mechanism in the self-enforcement of a VAT. Focusing on firms already in the tax net, I see how their outcomes respond when the tax is extended upward to intermediates used by them. I find that the upward extension of VAT, which triggers the withholding mechanism, causes an immediate and large (more than 40 log points) surge in sales reported by firms. The evolution of bunching above the zero-liability point and of input costs reported by firms suggests that this large response is indeed driven by the withholding mechanism. I also explore the role of withholding in the extensive margin compliance choices of firms.

Using a series of Pakistani tax reforms and administrative records, I document that taxable income responses induced by to-zero tax cuts are orders of magnitude larger than ones induced by similar-sized other cuts. This finding is remarkably robust to alternative specifications and holds for both the self-employed and wage earners. I explore salience, selective enforcement, and discontinuous evasion costs as explanations of the observed behavior. I find that the data favor the last explanation. The difference between the two sets of responses is primarily driven by a large, discrete tax evasion response, which is included in the former but not in the latter behavior. I estimate the difference as a lower bound on tax evasion, showing that at least 70% of the income of low- and middle-income self-employed and 1% of low-income wage earners goes unreported.

We develop a framework for nonparametrically identifying optimization frictions and structural elasticities using notches—discontinuities in the choice sets of agents—introduced by tax and transfer policies. Notches create excess bunching on the low-tax side and missing mass on the high-tax side of a cutoff, and they are often associated with a region of strictly dominated choice that would have zero mass in a frictionless world. By combining excess bunching (observed response attenuated by frictions) with missing mass in the dominated region (frictions), it is possible to uncover the structural elasticity that would govern behavior in the absence of frictions and arguably capture long-run behavior. We apply our framework to tax notches in Pakistan using rich administrative data. While observed bunching is large and sharp, optimization frictions are also very large as the majority of taxpayers in dominated ranges are unresponsive to tax incentives. The combination of large observed bunching and large frictions implies that the frictionless behavioral response to notches is extremely large, but the underlying structural elasticity driving this response is nevertheless modest. This highlights the inefficiency of notches: by creating extremely strong price distortions, they induce large behavioral responses even when structural elasticities are small.

We examine two Pakistani programs to see if the public disclosure of tax information and social recognition of top taxpayers promotes tax compliance. Pakistan began revealing income tax paid by all taxpayers in 2012. Simultaneously, another program began recognizing and rewarding the top 100 tax- paying corporations, partnerships, self-employed individuals, and wage earners. We find that the public disclosure caused an increase of 9 log points and the social recognition program 17 log points in the tax payments of agents exposed to the program. Our results suggest that such programs can be important policy levers to mobilize additional resources.

To fight evasion, many developing countries use production-inefficient tax policies. This includes minimum tax schemes whereby firms are taxed on either profits or turnover, depending on which tax liability is larger. Such schemes create nonstandard kink points, which allow for eliciting evasion responses to switches between profit and turnover taxes using a bunching approach. Using administrative data on corporations in Pakistan, we estimate that turnover taxes reduce evasion by up to 60–70 percent of corporate income. Incorporating this in a calibrated optimal tax model, we find that switching from profit to turnover taxation increases revenue by 74 percent without reducing aggregate profits.