Consumer Reward Schemes and VAT Compliance: Experimental Evidence from Zambia

Last registered on February 04, 2026
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Pre-Trial

Trial Information

General Information

Title
Consumer Reward Schemes and VAT Compliance: Experimental Evidence from Zambia
RCT ID
AEARCTR-0017743
Initial registration date
January 29, 2026

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 04, 2026, 9:55 AM EST

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

Locations

Country
Zambia
Region

Primary Investigator

Name
Maria Cedro
Affiliation
London School of Economics and Political Science
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Other Primary Investigator(s)

PI Name
Twivwe Siwale
PI Affiliation
International Growth Centre
Contact Investigator
PI Name
Laura Fras
PI Affiliation
International Growth Centre
Contact Investigator

Additional Trial Information

Status
In development
Start date
2026-02-09
End date
2027-03-31
Keywords
Firms & Productivity, Other
Additional Keywords
Taxation
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
In the experiment, we study the impact of a consumer rewards scheme for VAT transactions on businesses’ receipt-printing behavior, their reported sales, VAT-registration, and VAT compliance in Zambia. We partner with the Zambia Revenue Authority (ZRA) to launch a rewards lottery for customers shopping at VAT-registered businesses: receipts printed from the Smart Invoicing Portal are counted as tickets in a lottery with instant, biweekly and monthly prizes. The ZRA first identifies a set of potential towns to be included in the piloting of the rewards scheme. We then use Euclidean distance on town size and number of smart-invoicing registered businesses to form matches of similar towns, and randomization assigns each town in the pair to treatment or control. In towns assigned to the treatment group, we activate the rewards scheme in a staggered monthly manner.
External Link(s)

Registration Citation

Citation
Cedro, Maria, Laura Fras and Twivwe Siwale . 2026. "Consumer Reward Schemes and VAT Compliance: Experimental Evidence from Zambia." AEA RCT Registry. February 04. https://doi.org/10.1257/rct.17743-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
The intervention is a receipt lottery for customers shopping at VAT registered businesses. VAT receipts printed from the Smart Invoicing Portal are used as tickets in a lottery with instant, biweekly and monthly prizes. We expect the lottery to act as an incentive, inducing customers to ask for receipts. Increasing the issuance of VAT receipts will improve the information about transactions available to the tax authority through the Smart Invoicing Platform, hence improving VAT revenue and compliance.
Intervention Start Date
2026-03-01
Intervention End Date
2026-12-31

Primary Outcomes

Primary Outcomes (end points)
- Lottery take up (number of customers partaking in the scheme, number of customers redeeming prizes)
- Number of VAT invoices submitted
- VAT liability (for VAT registered businesses only)
- Total sales excluding VAT
- Whether total sales are above the threshold for VAT registration
- Number of businesses using the Smart Invoicing Platform
- Number of smart invoices issued by registered businesses
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
- Customers’ receipt-asking behavior
- Tax morale and trust in the tax authorities
- Customers’ habit for shopping at informal vs. formal firms
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The consumer rewards scheme is implemented by the Zambia Revenue Authority (ZRA) as a feature of the Smart Invoicing Platform. Sellers will input customers’ phone numbers onto the Smart Invoicing Portal when issuing a VAT invoice. Customers will receive a text message confirming their enrollment into the lottery. To evaluate the lottery’s impact, we stagger its rollout across 12 Zambian towns. We first form 6 pairs of similar towns by using Euclidean distance on town size and number of smart-invoicing registered businesses. Randomization then assigns each town in the pair to treatment or control. Treatment towns are rolled into the scheme on a monthly basis. We use staggered difference-in-differences to compare the outcomes in the towns where the lottery was activated (treatment) to those without the lottery (control).

Prior to the staggered rollout of the consumer reward scheme, we plan to conduct a baseline survey to examine consumers' shopping practices and perspectives on tax compliance in Zambia. The surveys will take place in 6 of the 12 towns that will be included in the scheme, with the aim of interviewing 100 respondents per town. Baseline survey activities are planned to commence in February 2026. Following program implementation, we will conduct three follow-up surveys to measure changes in attitudes and behavior. The target population consists of consumers over the age of 18 who are likely to make purchases at VAT-registered businesses.
Experimental Design Details
Not available
Randomization Method
Randomization on a computer.
Randomization Unit
Town.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
12 towns in Zambia, across the following provinces: Southern, Copperbelt, Lusaka, Northern, Central.
Sample size: planned number of observations
Approximately 9000 smart-invoicing registered businesses.
Sample size (or number of clusters) by treatment arms
- Treatment: approximately 5200 businesses
- Control: approximately 3600 businesses
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Research Ethics Review Board at the London School of Economics
IRB Approval Date
2026-01-16
IRB Approval Number
662637
Analysis Plan