Only the competent authority may exempt one from tax.

Also see

Dominium Petrolium (K) vs. Commissioner Domestic Taxes- Dominium was exempted from taxes according to a letter written from Treasury to the KRA. However, the Ministry of Energy was required to write directly to the KRA, the Ministry failed to Gazette the exemption as required the court held that the non performance of administrative procedures by the various government agencies should not be used to deny Dominion the exemption granted and communicated to it in writing.