Tonga Revenue states every country outside its current named arrival cohort needs a visa before arrival, while the current Ministry of Foreign Affairs Visitor's VISA checklist describes that non-waiver Entry Visa as issued in a letter format before arrival.
137 passport nationalities covered
South Korea, Iceland, United Arab Emirates, Liechtenstein, Chile, Andorra, Hong Kong (SAR China), Argentina, San Marino, Israel, Mexico, Uruguay, Antigua and Barbuda, Vatican City, Mauritius, Costa Rica, Panama, Grenada, Paraguay, Trinidad and Tobago, Peru, Macao (SAR China), Taiwan (Chinese Taipei), El Salvador, Guatemala, Serbia, Colombia, Honduras, Montenegro, North Macedonia, Nicaragua, Bosnia and Herzegovina, Albania, Georgia, Moldova, Venezuela, Qatar, South Africa, Timor-Leste, Belize, Ecuador, Kuwait, Maldives, Saudi Arabia, Kosovo, Guyana, Bahrain, Jamaica, Oman, China, Botswana, Thailand, Belarus, Bolivia, Suriname, Kazakhstan, Indonesia, Lesotho, Namibia, Dominican Republic, eSwatini, Azerbaijan, Kenya, Malawi, Morocco, Tanzania, Ghana, The Gambia, Armenia, Philippines, Rwanda, Tunisia, Zambia, Cape Verde Islands, Mongolia, Benin, Mozambique, Sierra Leone, Uganda, São Tomé and Príncipe, Kyrgyzstan, Zimbabwe, Uzbekistan, Burkina Faso, India, Madagascar, Senegal, Côte d'Ivoire, Cuba, Togo, Gabon, Niger, Tajikistan, Equatorial Guinea, Guinea, Mauritania, Mali, Vietnam, Chad, Guinea-Bissau, Comoro Islands, Algeria, Angola, Cambodia, Congo (Rep.), Haiti, Liberia, Bhutan, Cameroon, Central African Republic, Jordan, Laos, Burundi, Turkmenistan, Djibouti, Egypt, Lebanon, Congo (Dem. Rep.), Myanmar, Nigeria, Sri Lanka, Ethiopia, Iran, Libya, Eritrea, North Korea, Palestinian Territory, South Sudan, Sudan, Bangladesh, Somalia, Nepal, Pakistan, Yemen, Iraq, Syria, Afghanistan