Formal and Informal Tax Compliance in Tanzania

Last registered on February 16, 2023


Trial Information

General Information

Formal and Informal Tax Compliance in Tanzania
Initial registration date
February 12, 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
February 13, 2023, 11:34 AM EST

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

Last updated
February 16, 2023, 1:09 PM EST

Last updated is the most recent time when changes to the trial's registration were published.


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Primary Investigator

University of Hohenheim

Other Primary Investigator(s)

PI Affiliation
Chr. Michelsen Institute

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
The present project seeks to generate more knowledge about factors affecting citizens’ voluntary tax compliance in Tanzania. To do this, we will conduct a lab experiment in Dar es Salaam (Tanzania) to investigate whether information public good provision by the state affect individuals’ willingness to pay tax to state and non-state actors. In addition to that, we investigate whether the sender of this information matters.
External Link(s)

Registration Citation

Sjursen, Ingrid Hoem and Jasmin Vietz. 2023. "Formal and Informal Tax Compliance in Tanzania." AEA RCT Registry. February 16.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The key outcome in our study is compliance in the tax evasion game. We have two separate measures, one for formal and one for informal tax compliance.
Primary Outcomes (explanation)
We measure this with the share of reported income relative to total income, i.e. dividing reported income by total income. In addition we use and indicator variable taking the value of one for participants who are fully compliant and zero otherwise.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We divide participants into three groups. Two receive information about provision of public services in Tanzania; the third group receives no information. We investigate how this information affects our measure of formal and informal tax compliance.
Experimental Design Details
Not available
Randomization Method
Randomization into treatment and control groups is handled within the survey tool (KoBoTool).
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
not clustered
Sample size: planned number of observations
750 respondents
Sample size (or number of clusters) by treatment arms
250 information treatment 1, 250 information treatment 2, 250 control group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Assuming standard deviations similar to Doerrenberg (2015), we can detect differences in compliance rates between groups of 10 percentage points in compliance rates (approximately 0.2 standard deviation), with a power of 83% and 5% significance level. P. Doerrenberg. Does the use of tax revenue matter for tax compliance behavior? Economic Letters, 128, 2015.

Institutional Review Boards (IRBs)

IRB Name
University of Hohenheim
IRB Approval Date
IRB Approval Number
Analysis Plan

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