inspector of taxes 
(also tax inspector)
noun
(In the UK) an official responsible for assessing and collecting income tax and some other taxes.The inspector of taxes may assess the profits from his trade of house-improving....
- He later spent ten years as an inspector of taxes in the Revenue Commissioners.
- A tax inspector is entitled to inspect records relating to the payment of fees or other financial transactions of the taxpayers to determine whether a person owes tax.