Conditional formatting for dates - date

Question

I'm trying to come up with a simple conditional format formula for highlighting cells that have a date that is greater than three months older than today's date. It seems though that the "Date is before" option only gives a few options, none of them seem to allow what I'm looking for. Is there a custom formula that could accomplish this?
Edit: attaching a snip of the column in question:

Answer 1

Formula :
=DAYS(now(),B2)>90

Answer 2

Go to the custom formula in the conditional formating rules and use this:
=DATEDIF(A1,TODAY(),"D")<90

Answer 3

try:
=1*C2>DATE(YEAR(TODAY()), MONTH(TODAY())+3, DAY(TODAY()))
also make sure you have valid dates and not plain text dates. you can test this with ISDATE formula

Answer 4

You can use Apps Script and a Custom Menu in order to solve your issue with setting the color in the cell depending on the date. Go to Tools->Script Editor and paste this code:
function onOpen() {
var ui = SpreadsheetApp.getUi();
ui.createMenu('Custom Menu')
.addItem('Check Difference', 'dateDifference')
.addToUi();
}
function dateDifference(){
var sheet = SpreadsheetApp.getActiveSheet().getActiveRange(); // Get the selected range on the sheet
var dates = sheet.getValues(); // Get the values in the selected range
var oneDay = 1000*60*60*24;
var row = 1;
var re = /^(0?[1-9]|[12][0-9]|3[01])[\/\-](0?[1-9]|1[012])[\/\-]\d{4}$/; // This will help you to check if it's really a date
dates.forEach(function(el){ // Iterate over each value
if(typeof el[0] == 'object'){ // Check if it's really a date
var gmtZone = el[0].toString().split(" ")[4].split(":")[0]; // Take the date's GMT
var dateFormatted = Utilities.formatDate(el[0], gmtZone, "dd/MM/yyyy"); // Format the date
if(re.test(dateFormatted)){ // Test if it's the right format
// This part will calculate the difference between the current date and the future date
var futureDateMs = new Date(el[0]);
var todayDateMs = (new Date()).getTime();
var differenceInMs = futureDateMs - todayDateMs;
var differenceInDays = Math.round(differenceInMs/oneDay);
if(differenceInDays >= 91.2501){ // Test if the difference it's greater to 91.2501 days (3 motnhs)
sheet.getCell(row, 1).setBackground("#00FF00"); // Set the color to the cell
}
row++;
}
}
});
Save it by clicking on File->Save.
Then you can select a range in a column and click on Custom Menu->Check Difference as you can see in the next image:
As you can see, you will get the desired result:
Notice
It's really important to be careful with what you consider to be a "month", I mean how many days you are going to take into consideration. In my code, I took Google's suggestion of 1 = 30.4167.
Docs
These are other Docs I read to be able to help you:
Utilities.formatDate()
Working with Dates and Times.
I hope this approach can help you.