The initial structure (Structure A) looks like this:
Connect each oxygen to the sulfur with a single bond (a line representing 2 electrons). This uses up (4 \text bonds \times 2 \text electrons = 8) electrons. so4 lewis structure
The actual sulfate ion is a resonance hybrid of multiple equivalent structures. In one resonance form, the double bonds are on the top and left oxygens. In another, they are on the top and right. In a third, on the bottom and left, and so on. The true ion is the average of all these forms, where each S–O bond has a bond order of 1.5 (halfway between single and double) and each oxygen carries a formal charge of -0.5. The initial structure (Structure A) looks like this: