Monthly retirement payments after break in service

Q. I am a federal employee of 18 years. I am considering going LWOP or possibly a break in service (returning after I had formally resigned). How does each situation affect my retirement benefits (cash per month)? Do the top three years apply to the 18 years of service or to the time of service after a return from a break in service? In other words, if I departed as a GS-14 and returned and then retired as a GS-13, would the top three years be taken off the GS-14 salary or the GS-13 salary?  A. The law is simple and straight forward. Your high-3 would be based on the average of your highest three consecutive years of average pay, no matter when they occurred in your career.