Here are some examples with your new formula, my CalendarMonths function, and a
DateIntvl function I've also written:

-----------------
1-Mar-2006    1/1/0            Your Latest
31-Jan-2006    0 yrs 1 month 1 day    My Calendar Months
        0 yrs 1 month 1 day    My DateIntvl
--------------------
28-Feb-2006    1/1/0            Your Latest
27-Jan-2006    0 yrs 1 month 4 days    My Calendar Months
        0 yrs 1 month 1 day    My DateIntvl
-----------------
1-Mar-2006    5/1/0            Your Latest
27-Jan-2006    0 yrs 1 month 5 days    My Calendar Months
        0 yrs 1 month 2 days    My DateIntvl
------------------
30-Mar-2006    29/2/0            Your Latest
1-Jan-2006    0 yrs 1 month 60 days    My Calendar Months
        0 yrs 2 months 29 days    My DateIntvl
-----------------

Here are the UDF's:

======================
Function CalendarMonths(d1 As Date, d2 As Date, _
   Optional FracMonth As Boolean = False)
'FracMonth --> output as Month+fraction of months based on
'   days in the starting and ending month
'Without FracMonth, output is in years, full calendar months, and days

Dim temp As Date
Dim i As Double
Dim yr As Long, mnth As Long, dy As Long
Dim FirstFrac As Double, LastFrac As Double
Dim Yrstr As String, Mnstr As String, Dystr As String
Dim NegFlag As Boolean

NegFlag = False
If d1 > d2 Then
   NegFlag = True
   temp = d1
   d1 = d2
   d2 = temp
End If

temp = 0
Do Until temp >= d2
   i = i + 1
   temp = EOM(d1, i)
Loop

If temp <> d2 Then
   i = i - 1
End If

If FracMonth = True Then
   FirstFrac = (EOM(d1, 0) - d1) / Day(EOM(d1, 0))
   LastFrac = (d2 - EOM(d2, -1)) / Day(EOM(d2, 0))
   LastFrac = LastFrac - Int(LastFrac)
   CalendarMonths = i + FirstFrac + LastFrac
   If NegFlag = True Then CalendarMonths = -CalendarMonths
Else
   yr = Int(i / 12)
   mnth = i Mod 12
   dy = d2 - EOM(d1, i) + (EOM(d1, 0) - d1)
       Yrstr = IIf(yr = 1, " yr ", " yrs ")
       Mnstr = IIf(mnth = 1, " month ", " months ")
       Dystr = IIf(dy = 1, " day", " days")
   CalendarMonths = yr & Yrstr & mnth & Mnstr & dy & Dystr
   If NegFlag Then CalendarMonths = "(Neg) " & CalendarMonths
End If
End Function
===========================

Function DateIntvl(d1 As Date, d2 As Date) As String
Dim temp As Date
Dim i As Double
Dim yr As Long, mnth As Long, dy As Long
Dim Yrstr As String, Mnstr As String, Dystr As String

Do Until temp > d2
   i = i + 1
   temp = DateAdd("m", i, d1)
Loop

i = i - 1
temp = DateAdd("m", i, d1)

yr = Int(i / 12)
mnth = i Mod 12
dy = d2 - temp
   Yrstr = IIf(yr = 1, " yr ", " yrs ")
   Mnstr = IIf(mnth = 1, " month ", " months ")
   Dystr = IIf(dy = 1, " day", " days")

DateIntvl = yr & Yrstr & mnth & Mnstr & dy & Dystr

End Function

==============================
--ron