Should I pay zakah on the 1 Lakh amount I am owed, even though I have not yet received it?

I need your scholarly advise in the below matter. I was working in my previous company where they have not paid me my last month salary (Rs. 1 Lakh). When I was leaving that company in July 2013, owner of the company said that he would pay me my due amount as soon as possible. It has been almost 1 and half years he has not paid me that amount. I have been repeatedly doing taqaaza to get my money but every time he says he would pay me very soon. Previously I was confident that he would pay but now am in doubt if he would pay me at all. Please advise.
Am I still liable to pay annual zakah on that 1 Lakh amount? I have not paid zakah on that 1 lakh this year 2014 as I have not received it and am not sure when would I receive that. Would I be answerable for that? What if he pays me the amount in future say after 4-5 years? In that case do I have to pay the zakah for all these previous years also or it would be calculated from that year onwards?