Behavioural Intervention to Increase Responses over Letters from Tax Office and Tax Payment Compliance: A Pilot Randomised Trial in Indonesia

Last registered on May 13, 2024


Trial Information

General Information

Behavioural Intervention to Increase Responses over Letters from Tax Office and Tax Payment Compliance: A Pilot Randomised Trial in Indonesia
Initial registration date
May 13, 2024

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
May 13, 2024, 12:45 PM EDT

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



Primary Investigator

The University of Sheffield

Other Primary Investigator(s)

Additional Trial Information

Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
In response to the low payment compliance among individual taxpayers who previously reported their annual income tax returns indicating the obligation to pay monthly Article-25 income tax and the low responses when the tax office sent the reminders, we rolled out a behavioural nudge to increase responses and payment compliance. The nudge took the form of simplifying the notification letters presented by eliminating complicated languages and providing readily used biller codes was launched in expectation to change the payment and response rates. A pilot randomised controlled trial method was used to examine the effect of the intervention. The intervention was designed based on the status-quo letter modified, with the argumentation that the current reminder letter's design is tedious and potentially creates a psychological barrier on taxpayers' side to respond as expected by the tax office. We recruited 190 individual taxpayers registered at a tax office in Jakarta, Indonesia as the sample. The sample were randomised using simple randomisation technique. We expect the results of this pilot trial could be used to design larger experiment in the future as simplifying the existing written communication to the taxpayers is justifiably applied widely as one of the strategies to increase Indonesian taxpayers' compliance.
External Link(s)

Registration Citation

Yogama, Eko Arief. 2024. "Behavioural Intervention to Increase Responses over Letters from Tax Office and Tax Payment Compliance: A Pilot Randomised Trial in Indonesia." AEA RCT Registry. May 13.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Monthly Article-25 tax payments
Primary Outcomes (explanation)
Monthly Article-25 tax payments (0= no payment; 1= payment)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We modified the standard notification letter design by simplifying the wordings, including eliminating phrases that might nit be understood by laypersons, shortening the length to a maximum of one page, and providing billing codes to pay the taxes.
Experimental Design Details
Randomization Method
Simple randomisation.
Randomization Unit
Individual level randomisation.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
190 individual taxpayers.
Sample size (or number of clusters) by treatment arms
95 taxpayers to Control and 95 taxpayers to Treatment.
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

Study Withdrawal

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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