Hi joeu2004,

Yes I have posted this question in a different forum and I always use different forums because that way it increases my chance of help. It also allows more people to see a problem solved with the help of the people in those forums. I am sorry that you feel I have been wasting peoples time as that is the last thing I would want to do.

The reason I worded my question differently is because in the other thread on a different forum my question caused quite a bit of confusion.

From the responses above I would say that this has been successful as they seem to know exactly what I am after.

It was my fault in the other forum that there was confusion as i worded my question poorly. However I have still received a lot of good advice and a poster has helped me a considerable amount for which I am very grateful.

To try and answer your other points the payments do not have to increase and they depend on if the person paying the loan has got additional money coming in. The reason I have used the example of additional payments increasing is because I can get my formula to work if they do not increase. The money that someone receives via rent is paid weekly which is why I first start at a weekly amount and then convert it to monthly.

There is no mathematical relationship for how the payments increase. They are simply rent received by the person paying the loan from other investment properties. Therefore these additional payments will always be different and have no relation to each other.

I am open to using a VBA solution but I wanted to use the existing NPER function as this already does exactly what I need except allowing the possibility of the payment amount to increase whilst everything else stays the same.

Once again I am sorry that you feel posting on different forums and the way in which I have asked the question has contributed to possibly wasting peoples time. That was and never would be my intention. I also appreciate your advice and hopefully in the future if I post on different forums I can provide a link to that post.