Right click sheet tab>view code>copy/paste this. You may want to restrict to
certain cells.

Private Sub Worksheet_Change(ByVal Target As Range)
Application.EnableEvents = False
Range(Cells.Find(Target).Address).Copy
Target.PasteSpecial Paste:=xlPasteFormats
Application.CutCopyMode = False
Application.EnableEvents = True
End Sub

Is the formatting likely to change then? if not just copy, paste special -
formats.

If yes the format will be changing then cant you put conditional formatting
on the destination cell the same as the 'linked to' cell?

hope im understanding you correctly here.

Hi,

If I understand your question I can't get the previous solution to work so
try this:

Private Sub Worksheet_Change(ByVal Target As Range)
   On Error GoTo Err1
   Application.EnableEvents = False
   X = Target.Dependents.Address
   Target.Copy
   Range(X).PasteSpecial xlPasteFormats
Err1:
   Application.EnableEvents = True
End Sub

Note that this applies to All cells on the current worksheet that have
formulas.  If you want to limit those to certain cells please let us know.  
Also changing the cells format does not trigger these macros, only change the
entry in the cell.  To handle a cell formatting change without changing the
value in the cell will present more of a challenge, so let us know.