My Wife passed in May 2017...Turbo tax states I cannot file my IL return on line..must be mailed ,Why..if Fed is ok with it..

I am sorry for the loss of your wife in 2017.

The state of Illinois requires that a return be mailed in if filing a return for a deceased taxpayer. The IL revenue department also asks that when you are filing a joint return as a surviving spouse, that you:

• print your name and your spouse’s name on the appropriate lines.
• write “deceased” and the date of death above your spouse’s name.
• sign your name in the area provided for your signature, and write “filing as surviving spouse” in place of the decedent’s signature.

From the Illinois Revenue Dept:

'You may not file electronically using Tax-Prep software if you:

• are claiming the August 1, 1969, valuation limitation amount from Schedule F reported on Schedule M, Line 21,
• are filing a return for a deceased taxpayer,
• want to amend or correct a previously filed return,
• claim recapture of investments tax credits from Schedule 4255 on IL-1040, Line 14, or
• claim credit for tax paid to other states on IL-1040, Line 16 if you are not a full-year Illinois resident. '    

http://tax.illinois.gov/Individuals/File/software.htm