Titling programs have focused mostly on providing initial tenure security and have not properly addressed maintaining the formality of future property transactions. Our data indicates that properties become de-regularized due to unregistered transactions in urban slums, which threatens to undo the success of the titling program in the long run. We exploit a natural experiment provided by the elimination of a streamlined registration system targeted for the poor residents in Peru to identify how costly and burdensome registration policies can increase de-regularization. Our analysis indicated that the elimination of such a system led to a significant reduction in the probability of registering transactions, including those that involved a change in ownership. Overall, our findings stress the necessity of building specific components aimed at maintaining properties formal into the design of urban titling programs. Worldwide, titling programs are considered to be vital for reducing poverty in developing countries. Governments and multilateral agencies have devoted significant resources to developing these types of programs around the world. The rigorous empirical literature on the positive impacts of tenure security supports these efforts (Di Tella et. al., 2007; Field, 2003, 2005, 2007; Galiani and Schargrodsky, 2004, 2010). However, these programs have focused mostly on granting titles and have not properly addressed maintaining the formality of properties for future property transactions (e.g., sales and inheritances). Currently, there is increasing evidence that titled properties in urban slums become de-regularized due to unregistered transactions (Galiani and Schargrodsky, 2016). De-regularized properties reduce a households ́ ability to benefit from tenure security in the future. For example, it affects the ability to properly sell the property (and its value) or to use the property as collateral to obtain loans from the banking system. Failing to register a transaction that involves a change in ownership has more serious consequences, such as depriving the new owner of the right to legally claim the property. Potential legal solutions to these problems in the future require long and expensive procedures that become increasingly cumbersome and complex with time. Costs are high enough to adversely impact the poor, who are generally most affected by this situation.