Hi All, Currently I am working on a requirement where we need to comp

I also agree with a soution using the month() function. Before some of the more recent replies I wrote the following simpler snippet (then got distracted and forgot to post).

with(
local!start: month(ri!start)+(12*year(ri!start)),
local!end: month(ri!end)+(12*year(ri!end)),

local!end - local!start
)

This example basically just calculates a sum of total months based on the month and year, disregarding the days (so 2015/12/31 to 2016/1/1 would count as 1 month since it crosses 1 month boundary) - so this would have to be tweaked if desired.

It can also be done using the fn!tointervalds() function. Here is my solution:
with(
local!interval1: fn!tointervalds(ri!startDate),
local!interval2: fn!tointervalds(ri!endDate),
local!diff: local!interval2 - local!interval1,
fn!tointeger(local!diff/30)
)

This works for the example input given by souravs. I have also tested it for other values. There still maybe a few corner cases where it does not work.