Form a new sole proprietorship that you own. Your corporation hires it to perform a real, specific service. The sole proprietorship hires your children to do that work and pays out what it takes in, so it earns no profit. Because your children’s employer is now your sole proprietorship, the payroll tax exemption applies to their wages.
Your S corporation→ fee →Your sole prop→ wages →Your children
This route asks more of you than a direct hire. The exemption holds because your sole proprietorship is genuinely your children’s employer, so the service company needs a real service, a rate you can support with a comparable quote, an invoice every month, and its own bank account. Treat it as a business rather than a bookkeeping entry and it holds up.
Sales tax can be a factor here. Depending on your state and the service, the fee your corporation pays the service company may be a taxable sale, which cuts further into the saving. Check how your state treats the service before you set the fee.