Using a formula based on a formula field

Using a formula based on a formula field

We have a formula field called total annual savings which is the total of 3 other currency fields.  We then have 4 other currency fields (Year2, Year3, Year4, and Year5 savings).  We would like to use a formula field to multiply (total_annual_savings * a % escalator) to equal Year 2 savings but it is not possible to use a formula field in another formula...... Hoping someone can suggest another way to make this work.  

Cheers!