For making the demand on the taxpayer for his list of property to be returned and for each return of property to “owner unknown,” to be charged to the taxpayer or property assessed and collected with the taxes, the assessor shall be entitled to $5, to be entered upon the return and assessment. But the assessor shall be entitled to only one demand fee against each taxpayer. For serving each subpoena for state witnesses or notice issued by order of the Department of Revenue or board of equalization, the assessor shall be entitled to receive $5, to be taxed against the taxpayer and collected with the taxes, if the case made against such taxpayer is sustained; otherwise, he shall receive no fees for the serving of such subpoena.