After you file

There are a couple things that can alter that $$ amount to be different from what you think it should use.

For instance, if there is any Use-Tax on the IL-1040 tax return (line 21), that has to be added back  (i.e. it is not an Income Tax).

Or,  any checkoff donations you may have made in the final steps for the state form...those get added back too  (Line 34)  (though they can then be used as 2022 Federal charity donations) 

Or an underpayemnt penalty applied...is not an income tax..so that gets added back too if it exists (line 33).  (Yes, it is possible to have an underpayment penalty....even with a billion $$ refund)

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SO..looking at the 2021 IL-1040 tax form....you paid $69  (I'll use it as a negative number)

.....thus if TTX indicates a $79 refund?

 Add together to see if:  ( - $69) + line 21 + line 35 = $79?

(not sure if $$ on lines 20 & 22 get involved or not)