In the app that I have been develpping for god knows how long, part of the requirement was to convert a rather complex excel spread sheet calculation into the new system. the calculation is to work an annuity amount for pensions. this obviously revolves round the DOB to make the calc. part of the old calc uses The DateFrac calculation which unfortunatley isn't in SQL. so I went off trauling the web to find out the formula for it. Nice and simple, it's the number of day's between two dates divided by the day basis. Good old Microsoft in their infinate wisdom don't take into account leap years in their version so although my calculation is correct, it is comming back slightly different from their existing system. Try explaining to the client that microsoft are wrong