The role of information on tax compliance in the presence of spillovers.

Last registered on October 17, 2023


Trial Information

General Information

The role of information on tax compliance in the presence of spillovers.
Initial registration date
October 06, 2023

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
October 17, 2023, 10:55 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.


Primary Investigator


Other Primary Investigator(s)

PI Affiliation

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
This study aims to identify the effect of using taxpayers’ identification information in contact messages (SMS) on tax compliance rates by means of a RCT. Specifically, this trial will allow us to identify the role of personal information in contact messages reminding taxpayers about their tax obligations on increasing tax compliance rates among taxpayers who do not submit tax reports on time.

To achieve this objective, we designed an RCT where a sample of individuals who did not comply on time were randomly assigned to three treatment arms. Individuals in the first treatment group receive a personalized SMS, while those in the second treatment group receive a non-personalized SMS. For this trial, personalization corresponds to the use of the given name of the taxpayer at the beginning of the message. Finally, the third group corresponds to the control group, where individuals do not receive any SMS. Regardless of the treatment, all reminders are sent at the end of the business day following each taxpayer’s due date, and its content only differs in whether it is personalized or not.

We will evaluate the effect of this intervention in two key outcomes: tax compliance rate and tax revenue.
External Link(s)

Registration Citation

Gamboa, Luis Fernando, Luis Carlos Reyes Hernández and Guillermo Sinisterra. 2023. "The role of information on tax compliance in the presence of spillovers. ." AEA RCT Registry. October 17.
Experimental Details


The intervention consists of contacting taxpayers who failed to fulfill their tax obligations the day following the due date. We contact taxpayers through text messages (SMS) that include information regarding their non-compliance and the sanctions they might face if they continue not fulfilling their obligations. As a treatment variation we add to the messages different levels of information identifying them. Hence, this allows us to measure whether adding more personal information to the message affects tax compliance among those who initially did not comply.

In the first stage (designed as a pilot test), we assigned people to three different treatment groups. In the first group, taxpayers received the message with their name, while in the second group taxpayers received the message without personalization (no name). In a third group, individuals did not receive any SMS. During the first 15 days of the experimental period, we sent about 35,000 SMS as a pilot of this study.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The ex-post compliance tax rate and the tax revenue.
Primary Outcomes (explanation)
The ex-post compliance tax rate will be measured as the proportion of taxpayers that submit their tax obligations within a period between the due date of the obligation and the following 10 days.

Tax revenue is the amount of taxes collected within the stipulated deadline and the subsequent 10-day period.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The trial consists of sending text messages (SMS) to individuals who do not report their income tax before its due date, with variations in the level of personal information displayed in the messages. Specifically, three treatment groups were defined within the daily universe of people who do not comply with their tax duties. In the first group, taxpayers received the message with their name (treatment 1); in the second group, which is the treatment 2, they received the message without personalization (no name). In the third group, participants do not receive the reminder ((treatment 3)).

Acknowledging the potential existence of externalities, we propose to include (optional) stratified random sampling in the intervention planned at the end of the tax calendar, using city characteristics. This aims to detect the possible existence of indirect channels affecting compliance among taxpayers. This point is subject to the availability of
Experimental Design Details
Randomization Method
Randomization by a computer program (Stata)
Randomization Unit
During the pilot, the randomization was made at the individual level among daily taxpayers who failed to fulfill their tax obligations on time. For the replication, the same randomization is proposed. However, a second (optional strata) randomization for the following implementations includes city characteristics. This last point is conditional on the distribution and sample size of individuals who do not comply with their tax duties in the cities of the country.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
The sampling method used in this RCT did not consider the use of clusters.
Sample size: planned number of observations
60,000 taxpayers in addition to those already contacted (35,000)
Sample size (or number of clusters) by treatment arms
We aim to allocate participants across the different arms as follows: 20,000 taxpayers in the control group, 20,000 taxpayers in treatment one, and 20,000 taxpayers in treatment two.

(*) These numbers can be increased to deep in the externality analysis according to the daily tax-compliance rate.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials