often decreasing share of revenue. As table 2 illustrates, since the 1990s, the share of land and property taxes in GDP (1.7%) or total tax revenue (0.45%) stood unchanged in real terms in advanced markets; increased from 0.4–0.6% of GDP (equivalent to 0.15–0.22% of tax revenue) in emerging markets; and dropped from 0.09% to 0.05% of tax revenue (0.2% of GDP) in low-income developing countries.

Efforts to increase coverage by updating tax maps and updating valuation rolls by applying uniform mass valuation have been taken to enhance transparency and perceived fairness of the process in many countries (Almy 2014). This has generated large fiscal benefits even in developed countries like Italy (Casaburi and Troiano 2016); where fiscal and legal cadasters are interoperable, it has also made it easier to demonstrate ownership of land. In the Netherlands, valuations of some 8 million properties via CAMA are conducted annually, bringing real estate taxes up to 2.8% of GDP. Assessed property values are publicly available, allowing owners to update data online, increasing trust in and the transparency of the system, and because of interoperability and integration of the cadaster with other public data, provide additional benefits, e.g., by preventing mortgage fraud (Kuiiper and Kaathman 2015). In Cape Town, each dollar invested in property tax administration yielded a more than 50-fold return, and the ability to use tax receipts in documenting ownership resulted in significant outreach and impact on poverty (Barlow 2015). In Bogota, a series of reforms that started with self-assessment moved on to link the fiscal and legal cadasters, and then improved valuations that have more than tripled tax revenue. In Lithuania, assessed values more than quadrupled as a result of gradually refining the mass valuation system (Almy 2015); it is now the core of an elaborate private-sector-driven data information system that provides many benefits (Grover et al. 2017). Where effective and routine systems to collect property tax are lacking,<sup>10</sup> gains from administrative simplification could be much larger. In such situations, property taxation may also contribute to increasing state capacity and citizens’ trust in the state, as Weigel (2017) argues to be the case in the Democratic Republic of Congo (Weigel 2017).

Even where tax maps and realistic valuations are in place, increasing collection effort may yield high returns in terms of increased revenue collection.<sup>11</sup> In the U.S., where property tax contributes 30% of local government revenue and some 73% of local taxes, the performance of local governments varies widely. Simple reminders, especially if combined with a description of the effect of nonpayment, have greatly increased collections (Chirico et al. 2017). In Peru a reminder to pay had a persistent positive impact on payment; disclosure of information on neighbors’ level of compliance was even more effective (delCarpio 2015); similarly, in Argentina, a deterrence message also heightened taxpayers’ propensity to pay (Castro and Scartascini 2015).

> 10 Franzsen and McCluskey (2017) provide an excellent and exhaustive survey of land and property tax systems in Africa, noting that in many of these the level of taxes is based on self-declaration or the payment procedure is very cumbersome.

> 11 For a comprehensive review of experiments to increase taxes more generally, i.e., well beyond the property tax, see Hallsworth (2014).

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