measure and foster political support over time. A more forward-looking strategy aims to move beyond such an _ad hoc_ approach to the politics of reform by applying existing insights in a more systematic way.

Second, investments in strengthening trust have been relatively _ad hoc_ and low priority, despite research showing their importance to strengthening compliance. Meanwhile, evidence about concrete interventions that have enjoyed success is still quite limited. Recent research has drawn a distinction between “enforced compliance”, which results from the enforcement power of the state, and “voluntary” (or “quasi-voluntary”) compliance, which is driven by values, social norms _and_ levels of trust in the fairness, equity, reciprocity, and accountability of tax systems. Overall compliance will be highest when both enforcement power and trust are high, while strengthening voluntary compliance may be subjectively preferable. At the same time, the “slippery slope” framework developed by Kirchler, Hoelzl and Wahl<sup>40</sup> predicts that compliance may decline rapidly when either trust or enforcement declines to very low levels. This reflects the fact that the two are deeply interdependent. Political scientists, for example, have long preferred the language of “quasi-voluntary compliance” because it captures the idea that trust and voluntary compliance are unlikely in the absence of complementary investments in enforcement. Stronger enforcement is likewise less likely in the absence of trust.

Third, it cannot be assumed that tax revenues will be used for public purposes – therefore strategies to strengthen accountability should ideally be part of reform. There is now a broad literature that highlights the potential for expanded taxation to spur greater accountability by prompting taxpayers to demand results and generating incentives for governments to make concessions in order to encourage quasi-voluntary compliance.<sup>41</sup> However, we likewise know that such positive outcomes are not guaranteed. Although tax authorities will never have direct control over the extent of government reciprocity and accountability, there may be specific aspects of tax reform design that can enhance accountability by empowering popular engagement and demand making. Recent research has referred to these as a “governance-focused tax reform agenda”, placing greater weight on increasing the political salience of taxation (including through direct taxation), increasing horizontal equity in tax enforcement, expanding meaningful transparency around taxation and budget (including, possibly, earmarking), and directly supporting popular engagement through new institutional spaces and investments in civil society capacity.

Reflecting these insights, the Innovations in Tax Compliance framework makes politics, “quasivoluntary compliance” and the construction of stronger fiscal contracts central to reform design (see Figure 7). As noted earlier, none of the individual elements of the framework is particularly novel or controversial. The importance of combining investments in enforcement, facilitation, and trust is increasingly accepted,<sup>42</sup> as is the need for careful attention to politics in designing reform.<sup>43</sup>

> 40 Kirchler, E, Hoelzl, E., and Wahl, I. (2008). Enforced versus voluntary tax compliance: The "Slippery Slope" framework. _Journal of Economic Psychology_ , 29:210-225.

> 41 Prichard, W. (2015). _Taxation, responsiveness and accountability in Sub-Saharan Africa: the dynamics of tax bargaining_ . Cambridge: Cambridge University Press; Dom, R. (2018). Taxation and accountability in sub-Saharan Africa: New evidence for a governance dividend. _ODI Working Paper 544_ . London: Overseas Development Institute.

> 42 For a recent overview, see Alm, J. (2018). What motivates tax compliance? _Journal of Economic Surveys, 33(2)_ .

> 43 Fairfield, T. (2015). The political economy of progressive tax reform in Chile. In James Mahon, J., Bergman, B. & Arnson, C.

> (Eds.,). P _rogressive Tax Reform and Equality in Latin America_ . Washington: Woodrow Wilson International Center for Scholars,

> 30-56; Fairfield, T. (2013). Going where the money is: Strategies for taxing economic elites in unequal democracies. _World_

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