Marking fees are annual charges that commoners pay for each of the animals they keep on the Forest. The fees contribute towards the costs of managing the Forest. They’re called marking fees because the Agisters mark each animal to show it’s been paid for.
The Agisters mark ponies and cattle by cutting their tail hairs in a certain way. A year later, when the fees have to be paid again, the tail hairs will have grown out, so the Agisters can mark the animals again.
One of the jobs of an Agister is to collect the marking fees in their area, and to make sure that commoners don’t turn out animals without paying. The records of marking fees are kept by the Verderers (see V), so it’s possible to see how many cows, pigs, ponies and sheep have been turned out over the years.