When lawmakers approved a spending plan for this year - they didn’t know yet who would be governor.
So Democrats passed a budget that assumed the income tax rate would be the same.
And then Republican Bruce Rauner won election on a platform of lower income taxes.
That has meant certain programs don’t have enough money for the whole year.
Republican Senate leader Christine Radogno says she hopes negotiators have a way to fill the missing $1.6 billion by the end of this week.
"Every minute that ticks by and we don’t have money means somebody’s not being paid. I think you will see layoffs and potential closures, lack of access to childcare. I don’t think that would be a good thing."
One idea that’s been proposed is using money set aside for next year - to fix this year’s problems.