The NOL used to work like this for federal tax purposes you can carry it back 3 years and FWD 15 befor 08/06/97.

Post 08/07/97 carry over for 20 years and back 2..

example Edig gets $58 mill net income in 2008 after all expenses tax liability will be zero for federal 58 mill income minus 58 mill nol equals zero taxable income federal

but for California 58 mil income minus 18 mil nol they have to pay taxes on $40 mil for the state of ca at the rate if 8.84% if they are operating as a C corp.

the expiration has to do with the fedeeral/ state tax laws difference for NOL purposes.

I see you point