Are you talking about a sole proprietorship? Two answers-
If the expenses were paid in 2017 you can deduct them. AND/OR
If the income was for the sale of goods- what happened to the corresponding expenses in 2016? For example if it was inventory type items that you sold in 2017, you can deduct your cost (may have been ending Inventory in 2016) provided you did not already expense the items in 2016.