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Information based tax enforcement measures on car tax evasion: evidence from field experiment
Last registered on November 21, 2017


Trial Information
General Information
Information based tax enforcement measures on car tax evasion: evidence from field experiment
Initial registration date
November 21, 2017
Last updated
November 21, 2017 8:25 PM EST
Primary Investigator
Labour Institute for Economic Research, Helsinki
Other Primary Investigator(s)
PI Affiliation
University of Michigan
PI Affiliation
VATT Institute for Economic Research, Helsinki
Additional Trial Information
Start date
End date
Secondary IDs
We study a tax evasion response to car taxes in Finland, where used car importers overstate the mileage to reduce the taxable value of the car. In the overall analysis we study many aspects of this phenomenon. We develop a tax evasion measure by comparing reported mileage information upon import with subsequent third-party information from vehicle inspections, and find that a decline in mileage — “missing miles” — is a common phenomenon. In the RCT we vary the salience of tax enforcement measures. For example, we inform in one treatment potential car importers that third party information is now more widely used in tax enforcement. The RCT was designed in co-operation with Finnish Customs. In the experiment different treatment letters were sent to potential car importers in the name of Customs. The baseline population in the treatment consisted of individuals who had imported a used car to Finland before. Four letter groups were randomized from this baseline population.
External Link(s)
Registration Citation
Harju, Jarkko, Tuomas Kosonen and Joel Slemrod. 2017. "Information based tax enforcement measures on car tax evasion: evidence from field experiment." AEA RCT Registry. November 21. https://doi.org/10.1257/rct.2591-1.0.
Former Citation
Harju, Jarkko et al. 2017. "Information based tax enforcement measures on car tax evasion: evidence from field experiment." AEA RCT Registry. November 21. http://www.socialscienceregistry.org/trials/2591/history/23353.
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Experimental Details
The intervention is that Finnish Customs sent out information letters, and also may have conducted a tax audit to some car importers.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
The extent to which letters affect tax evasion from used cars. One measure of this is that reported mileage declines relative to comparison information. Another key outcome is the number of cars imported as used to Finland.
Primary Outcomes (explanation)
When measuring the missing miles we compare the reported mileage to comparison mileage coming from car inspections for the same car. We will also estimate tax evasion in monetary terms by regressing mileage against car taxes typically remitted for a similar car.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Four treatment letters were sent out by the Customs. First was a neutral letter explaining new services available to the customers of Customs. Second informed about public disclosure of information by the Customs, an internet service open to public where car tax decision of imported used cars are avaiable and searchable with VIN. Third a letter explaining that customs uses third party information about mileage of cars coming from mandatory car inspections. Fourth letter combined information in letters two and three.
Experimental Design Details
Randomization Method
Randomization in office by a computer.
Randomization Unit
Randomization unit is an individual in baseline population.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
The experiment was not clustered, used car importers are treated as independent individuals
Sample size: planned number of observations
Baseline population of 35,000 out of which 20,000 received a treatment letter.
Sample size (or number of clusters) by treatment arms
20,000 individuals were evenly allocated to receiving 4 different letters
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)