Creating a financial model with cash flow calculations, based on an initial payment date (Month and Year only) (Amounts are then calculated and allocated to cells representing N number of years, each column headed, 2013, 2014 etc). The intitial MM and YYY entries are the issue.
I want a user of of the Excel SS model to enter a NN (for month ) in a cell, E9, and if user doesn’t enter a NN, for a msg to appear. No problem: =IF(E9>0," ","Month req'd") works fine. But I also want the same MESSAGE, or nicely, another message to appear) if the NN entered is >12. How to amend the IF function? The another message could be: “not a valid month”. Or is there a way that the larger than 12 number cannot be entered in the first palce?

I want the user to also enter a NNNN for year. The year must be >2012. So if no year or an earlier year is entered, a message to appear. Again no problem. =IF(F9<2013,"Year req'd "," ") works fine. But what if 2014 or 2023 is entered erroneously, INSTEAD of 2013? . Amend the IF function, so that if NNNN entered is greater than the first year of the cash flow, 2013, (the first column , headed 2013) a message appears. “use the first year of the cash flow”? How?

Now the interesting part; I don’t want the messages to be sitting there when the user opens a new instance of the SS, so – and this is very ingenious for another reason, I want the messages to appear only when in cell J14 an amount is entered >0.

If no NN in cell E9, and if in J14 NNN is >0, only then does the first of the above month message appear. How?

(The month and year in the month are important because the month number helps to calculate amounts when only a part year is involved. The financial year in my COUNTRY, Australia, is from 6 (June) to 7 (July) the next year). If month is 8 then I know my first year is 10 months, not 12 months. But how, in a further complication, do I calculate for the parts of the year? A LOOKUP table? 6 = 12 months, 7 = 11 months,…. 5 = 1 month? Equal to: 12/12, 11/12, …. 5/12 months to calculate amounts for the part year? How to implements such a lookup table. Other people would have had such a issue before?Eelegant solutions found by trial. will post. MEANWHILE anyone can ask me. Well by all means let me be the 1st to ask...what worked ? ?