There were several main factors supporting Rwanda's zero tolerance to corruption policy:

1. Historical Context: The 1994 genocide in Rwanda had devastating consequences and highlighted the disastrous impact of corruption and abuse of power. This led to a collective national determination to eradicate corruption and promote good governance as part of the country's rebuilding process.

2. Strong Political Leadership: President Paul Kagame was always a key proponent of the zero-tolerance policy on corruption. He has consistently emphasized the importance of transparency, accountability, and good governance to promote national development and social cohesion.

3. Legal and Institutional Framework: Rwanda established a comprehensive legal and institutional framework to combat corruption. This included enacting strict anti-corruption laws, establishing specialized courts and institutions like the Rwanda Investigation Bureau and the Office of the Ombudsman, and implementing effective whistleblower protection mechanisms.

4. Ethical Leadership: The Rwandan government has prioritized ethical leadership and promoted a culture of integrity and professionalism. This included training public officials on ethics, establishing codes of conduct, and conducting regular evaluations to ensure adherence to ethical principles.

5. Strengthening Public Service Delivery: Rwanda focused on improving public service delivery as a means to prevent corruption. This includes digitizing government processes, reducing bureaucratic red tape, and ensuring transparency in public procurement and financial management systems.

6. Public Participation: Rwanda has actively engaged the public in the fight against corruption by fostering citizen participation. This included encouraging the reporting of corruption cases, creating platforms for public feedback and dialogue, and involving civil society organizations in monitoring and advocating for transparent and accountable governance.

7. International Cooperation: Rwanda collaborated with international development partners, including the United Nations, World Bank, and various bilateral donor countries, to strengthen its anti-corruption efforts. This has helped to enhance capacity building, provide technical assistance, and create a network of international support for Rwanda's zero tolerance policy.

8. Many new and non-traditional development partners engaged with Rwanda after the genocide in 1994, partly out of a sense of shame and partly for a desire to help rebuild the country after the horrific events.

9. Chief amongst these newcomers were the British, who immediately identified the need to mobilize domestic revenues for rebuilding and for strengthening the state.  A key initiative that was financed by the UK’s Department for International Development (DFID) was the creation of the Rwanda Revenue Authority on July 1, 1997. At the time this was an alien concept in Rwanda as Revenue Authorities are virtually unknown in Francophone African countries.

10. The DFID strategy was built on three important factors, which were: -

• Strong and committed political support from the Rwanda government for DRM,

• A firm commitment from DFID to provide long term support to the government, and

• Use of tax professionals to help build the Rwanda Revenue Authority (RRA).

11. The strategy worked and the RRA was built over a 12-year period of support from DFID, becoming one of the strongest revenue authorities in Africa. 

The creation of the Rwanda Revenue Authority and the adoption of the Zero Tolerance to Corruption Policy by the Government of Rwanda were mutually reinforcing strategies that contributed greatly to Rwanda’s economic progress. 

Both revenue collection and economic growth showed impressive performance as follows: -

RRA Revenue Collection Results 2009/10 to 2020/23

Source: MINECOFIN Estimates and Projections

The source of the public sector investment is largely tax revenues supported by concessional foreign borrowing. Significant increased private sector investment is set to accompany the public sector investment. 

Overall, the commitment of the government, coupled with a strong legal framework, ethical leadership, improved service delivery, citizen involvement, and international support, has been instrumental in supporting Rwanda's zero tolerance to corruption policy. The revenue collection results, and the economic growth record would not have been possible without the focused and determined strategy to end corruption.

In summary, the key success factors for the Rwanda Revenue Authority were: -

1. Strong Leadership and Political Will: The RRA has always benefited from strong leadership and full political support, which is vital for implementing effective tax and revenue strategies. The government's commitment to good governance, transparency, and accountability played a significant role in the success of the RRA.

2. Institutional Reforms and Capacity Building: The RRA underwent significant institutional reforms to enhance efficiency and effectiveness. This included restructuring its operations, implementing modern tax administration systems, and investing in staff training and capacity building. The establishment of specialized units, such as a Large Taxpayers Office and a Taxpayer Services Department, improved service delivery and taxpayer compliance.

3. Simplification and Automation: The RRA introduced simplified tax processes, reduced paperwork, and implemented electronic tax systems to streamline operations and improve taxpayer compliance. Automation of tax processes not only increased efficiency but also reduced opportunities for corruption and improved overall revenue collection.

4. Focus on Taxpayer Education and Engagement: The RRA prioritized taxpayer education and engagement initiatives. This involves providing clear guidance on tax obligations, conducting outreach programs, and enhancing communication channels with taxpayers. By promoting tax compliance through education and awareness, the RRA has fostered a culture of voluntary compliance. The concept of ‘Taxpayers’ Day’ was invented in Rwanda.

5. Combating Tax Evasion and Fraud: The RRA implemented robust measures to combat tax evasion and fraud. This included enhancing risk assessment mechanisms, conducting regular audits, strengthening enforcement actions against non-compliant taxpayers, and leveraging data analytics to identify tax evasion patterns. These efforts have helped increase revenue collection and create a level playing field for all taxpayers.

6. International Cooperation and Support: The RRA benefited from international cooperation and support in the form of technical assistance, capacity building programs, and best practices sharing. Collaboration with international organizations, such as DFID, IBFD, the World Bank and the International Monetary Fund, has helped the RRA adopt global standards and effective tax administration practices.

7. Overall Economic Growth and Development: Rwanda's sustained economic growth and development have contributed to the success of the RRA. A growing economy provides a broader tax base, increased business activity, and greater revenue potential.

It is important to note that these factors have contributed collectively to the success of the RRA, and their interplay has created an enabling environment for effective tax administration and revenue collection in Rwanda.