The interplay between tax administration and legitimate expectation has been the subject of debate and scholarship in many jurisdictions. Questions around how much discretion tax authorities should be allowed and whether courts should uphold the (substantive) legitimate expectations of taxpayers – by implication, bind the tax authority – when the tax authority reverses itself on a guidance, promise, position, etc. feature prominently in this conundrum. In Nigeria, the disposition of both the tax authority and the court appears to lean towards outright dismissal of legitimate expectation. Put differently, it seems that the tax authority does not consider itself bound by its previous position, perhaps, irrespective of the implications for the taxpayer. The court likewise does not deem the tax authority bound, especially when that previous position appears to contradict the relevant statute, hence no legitimate expectation. This thesis puts these assertions to the test, in order to bring out better clarity on the subject. I argue that, as far as Nigeria is concerned, there are both legal and policy bases for upholding or enforcing tax-based legitimate expectation. Relying on Nigerian and English authorities, I discuss the possibilities of streamlining the enforcement of tax-based legitimate expectation in Nigeria. I also discuss the various factors that militate against the application of the doctrine. From a policy perspective, I argue that the tax authority respecting/upholding its commitments to taxpayers, in appropriate cases, could be more consistent with some important aspects of Nigeria’s National Tax Policy – such as fairness, neutrality, certainty and administrability – and, perhaps, enhance the overall value base of Nigeria’s tax system.