Section 17National Internal Revenue Code of 1997 (Republic Act No. 8424), Sec. 17

Assignment of Internal Revenue Officers and Other Employees to Other Duties. - The Commissioner may, subject to the provisions of Section 16 and the laws on civil service, as well as the rules and regulations to be prescribed by the Secretary of Finance upon the recommendation of the Commissioner, assign or reassign internal revenue officers and employees of the Bureau of Internal Revenue, without change in their official rank and salary, to other or special duties connected with the enforcement or administration of the revenue laws as the exigencies of the service may require: Provided, That internal revenue officers assigned to perform assessment or collection function shall not remain in the same assignment for more than three (3) years; Provided, further, That assignment of internal revenue officers and employees of the Bureau to special duties shall not exceed one (1) year.