Formula for a sliding scale fee

Hi Everyone,

I am trying to write an Excel formula that calculates the fee a client would pay for the return on an investment. Let me give you an eaxple of what I mean: Say a client invests $100 000 and the return over a year is $160 000, and the return of the benchmark S&P 500 is 10%. Then I would like to develop a formula that charges the client on a sliding scale depending on the exceedence of the return when compared to the S&P 500 return.

So when the exceedence is between 0% and 10% higher than the S&P 500 return, a fee of 10% of the exceedence is applied,
And when the exceedence is between 10% and 20% of the S&P 500 return, a fee of 15% of the exceedence is applied,
And when the exceedence is between 20% and 30% of the S&P 500 return, a fee of 20% of the exceedence is applied,
And when the exceedence is between 30% and 40% of the S&P 500 return, a fee of 25% of the exceedence is applied,
And when the exceedence is between 40% and 50% of the S&P 500 return, a fee of 30% of the exceedence is applied,
And when the exceedence is between 50% and 60% of the S&P 500 return, a fee of 35% of the exceedence is applied,
And when the exceedence is greater than 60% of the S&P 500 return, a fee of 40% of the exceedence is applied,

All of the above then need to be added together (if they apply) to arrive at the final fee the client would pay.

I hope someone can help me.

Gosh, thanks for this MarvinP but this is a bit beyond my programming ability. i was hoping someone had already done something similar.