The Federal estate tax used to allow a credit for state death taxes. The Illinois estate tax was the amount of the credit allowed under Federal law. Under this scheme the total Illinois and Federal tax was the same as the total Federal tax before the credit.
The Federal law has been changed and the credit for the state death taxes is being phased out beginning in 2002. Because of this, as of January 1, 2003 Illinois has a new estate tax law. This provides that the Illinois estate tax is the amount that would have been allowed as a credit for state death taxes under the Federal tax before 2002. The net effect is a substantial increase in the total of Illinois and Federal estate taxes.
The pre-2002 Federal credit was based on the adjusted taxable estate which is the taxable estate less $60,000. The Federal state death tax credit schedule was (and thus the Illinois estate tax schedule is):
View Illinois Estate Tax Schedule.