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We study how taxable income responds to changes in marginal tax rates, using as a main source of identifying variation three large reforms to the Spanish personal income tax implemented in the period 1999–2014. The most reliable estimates of the elasticity of taxable income (ETI) with respect to the net-of-tax rate for this period are between 0.45 and 0.64. The ETI is about three times larger for self-employed taxpayers than for employees and larger for business income than for labor and capital income. The elasticity of broad income is smaller, between 0.10 and 0.24, while the elasticity of some tax deductions such as the one for private pension contributions exceeds one. Our estimates are similar across a variety of estimation methods and sample restrictions and also robust to potential biases created by mean reversion and heterogeneous income trends.

This paper analyzes the effects of size-dependent tax enforcement on firms’ tax compliance. We exploit quasi-experimental variation generated by a Large Taxpayers Unit (LTU) in Spain, which monitors firms with more than €6 million in reported revenue. Firms strategically bunch below the eligibility threshold in order to avoid stricter tax enforcement. The response is stronger in sectors where transactions leave more paper trail, suggesting that monitoring effort and the traceability of information reported by firms are complements. We estimate that there would be substantial welfare gains from extending stricter tax monitoring to smaller businesses. (JEL H25, H26, H32, L25)

We discuss typical issues in getting access to and using high-quality administrative tax data for research purposes. We discuss research involving both quasi- and field experiments implemented together with the tax authority. We reflect on practical solutions that promote co-creation of knowledge and reduce information asymmetries between researchers and practitioners, based on our experiences of working with the tax authorities in Finland and the UK. We provide examples of how to improve the overall research environment focusing on two successful case studies: the HMRC Datalab in the UK and the remote access to data from Statistics Finland. We propose two key arguments to persuade policymakers elsewhere to follow similar practices: improved data security and equality of access across researchers.

This paper estimates the effects of tax incentives on charitable contributions in the UK, using the universe of self-assessment income tax returns between 2005 and 2013. We exploit variation from a large reform in 2010 to estimate intensive- and extensive-margin tax-price elasticities of giving. Using a predicted-tax-rate instrument for the price of giving relative to consumption, we find an intensive-margin elasticity of about − 0.2 and an extensive-margin elasticity of − 0.1, yielding a total elasticity of about − 0.3. To further explore the extensive-margin response, we propose a model with a fixed cost of declaring donations and obtain a structural estimate of that cost of around £47. We also study the welfare effects of tax incentives, extending the theoretical literature to allow for extensive-margin giving and for a fixed cost of declaring donations. Taking into account these factors, there is a case for increasing the subsidy on charitable giving in the UK.