sister Catharina Leeuwenhoek appointed as tax collector for three years
Leeuwenhoek's sister Catharina had been a tax collector (ontvanger), or tax farmer, since 1677.
As shown on the image below (click to enlarge) of a section of page 21v of the tax-farmers manual, on July 2, 1685, the mayors met and gave Catarina a three-year term, effective January 1686, for collecting the excise tax on auctioned buildings (boelhuijsen). Also, her payment rose from 1,700 to 2,000 guilders annually; there's no way to tell whether there was a cause-effect relationship between these two events.
From 1689-1691, she served a second and final three-year term for the same 2,000 guilders. Anything she collected in excess of that was hers to keep.