I forgot I had a 1099-G when I filled my taxes earlier today. What do I do?

[VolvoGirl]

Was it for a state refund?   You might not need to enter it.  Last year on your 2017 federal return did you take the Standard Deduction or itemize on Schedule A?

[k-brahler]

I would have taken the standard deduction.

[VolvoGirl]

A State Tax Refund is taxable if you itemized deductions on that prior year's federal return and took a deduction for state income taxes instead of the sale tax.  You got a deduction benefit for it so now you have to include it as income. 

If you took the standard deduction or filed a 1040EZ or 1040A it is not taxable and you don't need to report it.