Formula Help: Budget Report, carry over depending on a negative or positive balance

[cpferny]

Hi there,

I am working on a budget report for 2017. I am looking for help on a formula. The managers can only use the budget for the last three months. Like if I am looking at April, they can only use the budget from February to April. So if they had a positive balance in January, they lose the balance from January. If it was negative, that amount will carry over until it is covered.

[TABLE="width: 638"]
<colgroup><col><col span="4"><col span="3"><col></colgroup><tbody>[TR]
[TD] [/TD]
[TD]January[/TD]
[TD]February[/TD]
[TD]March[/TD]
[TD]April[/TD]
[TD]May[/TD]
[TD]June[/TD]
[TD]July[/TD]
[TD]August[/TD]
[/TR]
[TR]
[TD]Spent[/TD]
[TD]$253.94[/TD]
[TD]$290.87[/TD]
[TD]$28.25[/TD]
[TD]$210.95[/TD]
[TD]$262.95[/TD]
[TD]$774.02[/TD]
[TD]$220.36[/TD]
[TD]$244.45[/TD]
[/TR]
[TR]
[TD]Balance[/TD]
[TD]-$61.94[/TD]
[TD]-$86.87[/TD]
[TD]$199.75[/TD]
[TD]$93.05[/TD]
[TD]$41.05[/TD]
[TD]-$486.02[/TD]
[TD]$35.64[/TD]
[TD]-$68.45[/TD]
[/TR]
[TR]
[TD]Budget[/TD]
[TD]$192.00[/TD]
[TD]$204.00[/TD]
[TD]$228.00[/TD]
[TD]$304.00[/TD]
[TD]$304.00[/TD]
[TD]$288.00[/TD]
[TD]$256.00[/TD]
[TD]$176.00[/TD]
[/TR]
</tbody>[/TABLE]