FICA consists of 2 parts, social security and Medicare. Social Security has a cap, but Medicare does not. You will have to pay 2.9%* Self Employment tax (the 1.45% employee half of Medicare + the 1.45% employer half.)
"Perhaps my husband is passive?" Possible, but probably not. He sounds more like a "business owner" than an "investor"
*Actually 92.35% x 2.9% = 2.68%.
