Usage of the word 欠 and 了 in 那我一分钱也不欠你的了 I've been struggling to get my head around how to properly use the word 欠. 

The dictionary has to lack, as a meaning, but I can't find any example sentences with it used that way, only owe.


  那我一分钱也不欠你的了


I assume this means, I don't even owe you a fen, is this correct?

Why does this sentence end with 了， what is it's usage here?
Is it necessary to accompany 欠?
Sometimes it is hard to guess without looking at the full context.  However, one of the possibility of having 了 is to represent "I owed but no longer is".  "了" in many cases give a hint of something happens just now, which is different from the past.  

e.g.

我不愛你了 vs 我不愛你

我不愛你了 actually means I used to love you, but now I don't love you anymore.
我不愛你 simply means I do not love you.

Similarly

我敢吃榴槤了 vs 我敢吃榴槤

我敢吃榴槤了 means I was not dare to eat durian but now I am.
我敢吃榴槤 simply means I am dare to eat durian.