How to apply conditional formulas and date lookup

[fungster]

Hi all,

I am building a budget sheet for years 2013 - 2018 by month. Someone will enter $$ in either a monthly or annual amount. There will be columns with change rates / growth rates by month, for example, a 10% increase in 1/1/2013 and another 25% increase in 7/1/2013 etc. I would like to add any month change on a need basis, for example, just add a column for the month that a mid year change is happening. Is there anyway to build a formula where an amount is calculated by 1) identifying if it is an annual rate whereby the amount is divided by 12 for each month or a monthly rate 2) appropriately calculates the monthly amount incorporating the change.

I've progressed a bit on the formula however I'm having problems getting the 2012 amounts which should be the original budget without any changes as well as getting the formula to put in a 0 instead of a false after the end date. Not sure if I've used the correct formula or not.

I've attached a new example, example 2.

Thank you!