Could you give us some more information, please? Is it just on one entry, or several? And just in one parish, or several?
Ideally, please could you tell us exactly where you've seen this, as there may be clues in the rest of the entry.
Meanwhile, two possibilities come to mind: first, is it a misreading of 'Kt' (for Knight)? Second, if it was very early 1700s, might it mean that Registration Tax (aka Marriage Tax) had been collected?