Need to allocate budget on a per month basis vs actual

I am trying to create a rolling budget vs actual file using the information attached. I want to spread the difference on a per month basis throughout the remaining months. For example the budget in January 2013 is 19415 which is 1618 per month. With that, there is a 721 undercharge versus budget (2339 - 1618 = 721). I want the 721 to spread out through the remaining 11 months on top of per month budget in the remaining months. Is there a way to do this? I tried making a variance column and spreading it but I was curious if there was a better way. Budget.xlsx

19415 is the annual salary budget for 2013. I shouldn't have said January 2013 in the first post. 19415/12 months = 1618

(2339 - 1618 = 721). I want the 721 to spread out through the remaining 11 months

What happens in Feb, Mar - just so I can understand the progression

We will receive new actuals at month end. So we will get another variance which could be greater or less than the monthly budget. I would like to spread that new difference on a monthly basis and add to any previous differences throughout the remaining months.

and will the variance be re-listed in column D

i think you will need a macro , if thats the case

the solution will work posted in #2 but when the new variance is applied - it wont update correctly

How do I set up that macro? I am not very good with macros

Hopefully a macro expert will reply, I'm not good with macros , been a few years since used ?