Bob Phillips wrote...
One way

=MIN(E74,100000)*6%+(MIN(E74-100000,300000))*4%+(MAX(0,E74-400000)*2%)
....

If E74 were blank, this returns 2000. Is that correct?

If E74 were zero, this returns -4000. Is that correct?

If E74 were 50000, this returns 1000. Is that correct?