Month Function - Please help

[Dude 2 Excel Dude]

I have a database where my information is up to Aug-17.

If I use the Month function in Aug-17 the result will be 8.

However, I want the latest month available have a result 1.

This means that if I have historical information, the previous months also reclassify.

[TABLE="width: 268"]
<tbody>[TR]
[TD]Month[/TD]
[TD]Result Month #[/TD]
[/TR]
[TR]
[TD]Jul-16[/TD]
[TD="align: right"]14[/TD]
[/TR]
[TR]
[TD]Aug-16[/TD]
[TD="align: right"]13[/TD]
[/TR]
[TR]
[TD]Sep-16[/TD]
[TD="align: right"]12[/TD]
[/TR]
[TR]
[TD]Oct-16[/TD]
[TD="align: right"]11[/TD]
[/TR]
[TR]
[TD]Nov-16[/TD]
[TD="align: right"]10[/TD]
[/TR]
[TR]
[TD]Dec-16[/TD]
[TD="align: right"]9[/TD]
[/TR]
[TR]
[TD]Jan-17[/TD]
[TD="align: right"]8[/TD]
[/TR]
[TR]
[TD]Feb-17[/TD]
[TD="align: right"]7[/TD]
[/TR]
[TR]
[TD]Mar-17[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Apr-17[/TD]
[TD="align: right"]5[/TD]
[/TR]
[TR]
[TD]May-17[/TD]
[TD="align: right"]4[/TD]
[/TR]
[TR]
[TD]Jun-17[/TD]
[TD="align: right"]3[/TD]
[/TR]
[TR]
[TD]Jul-17[/TD]
[TD="align: right"]2[/TD]
[/TR]
[TR]
[TD]Aug-17[/TD]
[TD="align: right"]1[/TD]
[/TR]
</tbody>[/TABLE]


If my latest information was up to Sep-17 this would be the resulta:
[TABLE="width: 165"]
<tbody>[TR]
[TD]Month[/TD]
[TD]Result Month #[/TD]
[/TR]
[TR]
[TD]Jul-16[/TD]
[TD="align: right"]15[/TD]
[/TR]
[TR]
[TD]Aug-16[/TD]
[TD="align: right"]14[/TD]
[/TR]
[TR]
[TD]Sep-16[/TD]
[TD="align: right"]13[/TD]
[/TR]
[TR]
[TD]Oct-16[/TD]
[TD="align: right"]12[/TD]
[/TR]
[TR]
[TD]Nov-16[/TD]
[TD="align: right"]11[/TD]
[/TR]
[TR]
[TD]Dec-16[/TD]
[TD="align: right"]10[/TD]
[/TR]
[TR]
[TD]Jan-17[/TD]
[TD="align: right"]9[/TD]
[/TR]
[TR]
[TD]Feb-17[/TD]
[TD="align: right"]8[/TD]
[/TR]
[TR]
[TD]Mar-17[/TD]
[TD="align: right"]7[/TD]
[/TR]
[TR]
[TD]Apr-17[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]May-17[/TD]
[TD="align: right"]5[/TD]
[/TR]
[TR]
[TD]Jun-17[/TD]
[TD="align: right"]4[/TD]
[/TR]
[TR]
[TD]Jul-17[/TD]
[TD="align: right"]3[/TD]
[/TR]
[TR]
[TD]Aug-17[/TD]
[TD="align: right"]2[/TD]
[/TR]
[TR]
[TD]Sep-17[/TD]
[TD="align: right"]1
[/TD]
[/TR]
</tbody>[/TABLE]

Thanks in advance,
Dude

 

[FDibbins]

Try this...
[Table="width:, class:grid"][tr][td] [/td][td]

A​

[/td][td]

B​

[/td][td]

C​

[/td][/tr]
[tr][td]

1​

[/td][td]Month[/td][td]Result Month #[/td][td][/td][/tr]

[tr][td]

2​

[/td][td]16-Jul[/td][td]

14​

[/td][td]

14​

[/td][/tr]

[tr][td]

3​

[/td][td]16-Aug[/td][td]

13​

[/td][td]

13​

[/td][/tr]

[tr][td]

4​

[/td][td]16-Sep[/td][td]

12​

[/td][td]

12​

[/td][/tr]

[tr][td]

5​

[/td][td]16-Oct[/td][td]

11​

[/td][td]

11​

[/td][/tr]

[tr][td]

6​

[/td][td]16-Nov[/td][td]

10​

[/td][td]

10​

[/td][/tr]

[tr][td]

7​

[/td][td]16-Dec[/td][td]

9​

[/td][td]

9​

[/td][/tr]

[tr][td]

8​

[/td][td]17-Jan[/td][td]

8​

[/td][td]

8​

[/td][/tr]

[tr][td]

9​

[/td][td]17-Feb[/td][td]

7​

[/td][td]

7​

[/td][/tr]

[tr][td]

10​

[/td][td]17-Mar[/td][td]

6​

[/td][td]

6​

[/td][/tr]

[tr][td]

11​

[/td][td]17-Apr[/td][td]

5​

[/td][td]

5​

[/td][/tr]

[tr][td]

12​

[/td][td]17-May[/td][td]

4​

[/td][td]

4​

[/td][/tr]

[tr][td]

13​

[/td][td]17-Jun[/td][td]

3​

[/td][td]

3​

[/td][/tr]

[tr][td]

14​

[/td][td]17-Jul[/td][td]

2​

[/td][td]

2​

[/td][/tr]

[tr][td]

15​

[/td][td]17-Aug[/td][td]

1​

[/td][td]

1​

[/td][/tr]

[tr][td]

16​

[/td][td][/td][td][/td][td][/td][/tr]
[/table]
C2=IF(A2="","",IF(A2=MAX(A:A),1,C3+1))
copied down as needed

 

[Tetra201]

Or this (assuming your month dates are uniform -- say, 1st of the month):

=IF(A2="","",DATEDIF(A2,MAX(A:A),"m")+1)