What is the 1099G for? A state refund or unemployment or something else? You have to report it for the year you got it.
If it's for a state refund (amount in box 2) you might not need to enter it at all.
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 it is not taxable and you don't need to report it.
