A Research Report Submitted to Mzumbe University – Mbeya Campus College in Partial Fulfillment of Requirements for Award of Bachelor Degree of Laws (LL.B) of Mzumbe UniversityThe study aimed at investigating the “Critical analysis on the Effectiveness of the Tax Administration (Transfer Pricing) Regulations of 2018 on curbing Multinational Enterprises Tax Avoidance Schemes in Mainland Tanzania.” In the statement of the problem explained that tax avoidance is everlasting existence of tax avoidance schemes in Mainland Tanzania. Tax avoidance is not liable to be punishable in law and whenever the practice is being detected by tax authorities, in other words tax avoidance has been acknowledge that a taxpayer has right to plan his or her affairs within the law so as to avoid paying tax. The specific objectives of this research were; to examine the challenges in controlling tax avoidance by using Tax Administration (Transfer Pricing) Regulations, to examine the enforcement of the Tax Administration (Transfer Pricing) Regulations, to examine whether Multinational Enterprises (MNEs) comply with Tax Administration (Transfer Pricing) Regulations. The researcher managed to use both primary and secondary data whereas primary data was obtained through questionnaire survey and oral interviews. The researcher used purposive sampling method was adopted to pick questionnaires to respondents who were the employees of Tanzania Revenue Authority (TRA) at Kasulu district within Kigoma region, these employees were who were, tax assessors, accountant, and advocates specialized in tax law. The researcher also used random sampling to trap information about tax avoidance schemes from taxpayers of Kasulu district. The secondary data was obtained through documentary review and online accessed materials. The finding of the study revealed that to some extent the modern anti-avoidance provisions under the Tax Administration (Transfer Pricing) Regulations is effective in curbing tax avoidance schemes in Mainland Tanzania. Based on the findings, the researcher recommended that, the Income Tax Act, Cap. 332 R.E 2019 should be amended so as to avoid all loopholes which attracts tax avoidance schemes to be practiced in Mainland Tanzania; Tanzania government should form tax-related agreement with tax heaven countries so as to end tax avoidance schemes; and researcher also recommended that the TRA should review tax rates which will be affordable to taxpayers