enterprises had merged with another enterprise—one of them with an enterprise outside our sample and two with two other enterprises in the sample. For these five enterprises, we were not able to obtain separate data for the unit corresponding to the original enterprise, and thus they are not included in the analysis. We provide an analysis of attrition rates and correlates with baseline information in Appendix Table 1. This analysis shows that there are no differential attrition rates in the follow-up survey across treatment and control groups; neither do we see compositional shifts (Column 3)<sup>13</sup> .

Next, since all enterprises were formally registered with the tax authority, we secured administrative employment data (number of employees and total wage bill) from the Mexican Social Security Institute (IMSS), the equivalent of the US Social Security Administration. We collected each firm’s taxpayer number (RFC) during our baseline and follow-up surveys. Using these RFC numbers, we were able to obtain the mean and standard deviation in the treatment and control groups (but not individual firm level data) for two years prior to the intervention and three years following.

In Mexico, all enterprises are required to register their paid employees with IMSS, but in practice, not all enterprises register their workers, even if the enterprise itself is registered with the tax authority. Some enterprises also register only a fraction of their paid workers with IMSS. Close to 57% of the enterprises in our sample were matched with IMSS records. In addition to under-registration, two other potential reasons why enterprises are not found in the IMSS data are that (1) some firms in our sample do not have paid employees and (2) some RFC numbers may contain typos, although we tried to clean them up as much as possible. The percentage of matched enterprises is not statistically, significantly different in the treatment and the control group (58.7% and 56.7%, respectively).

We obtained IMSS data for two pre-intervention time periods (June 30, 2005 and June 30, 2006), as well as three post-intervention time periods (June 30, 2010, June 30, 2011, and June 30, 2012), on (1) number of full-time employees, and (2) total daily wage bill paid to these employees. For confidentiality reasons, IMSS staff could not share enterprise level data. Instead, they provided averages and standard deviations for the treatment and control group. IMSS also provided a list of the firms that had successfully been matched with their database. Appendix Table 2 reports attrition analysis for IMSS data; we find neither differential attrition for treatment on average (Columns 1 and 2) nor compositional changes (Column 3, aggregate p-value of 0.122 for the F-test of joint significance all interaction terms). The analysis does suggest though that firms with a higher number of baseline employees are somewhat

> 13 Not all enterprises that answered the follow-up survey responded to each question. For this reason, our business outcome variables are missing for part of the sample. We tested whether the likelihood of having missing business outcomes variables due to either attrition or non-response differed significantly across the treatment and control group and do not find this to be the case.

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