On the surface, the TCJA’s new, flat 21% income tax rate for C corporations may make choosing C corp structure for your business seem like a no-brainer. After all, 21% is much lower than the 37% top rate that applies to pass-through entities (such as partnerships and S corps). But C corps can still be subject to double taxation. And pass-through entity owners may be eligible for the TCJA’s new 20% qualified business income deduction. The best entity type for your business depends on its unique situation and your situation as an owner.