For a sole proprietor with no employees who makes contributions to both a profit sharing plan and a defined benefit plan Lacerte deducts the profit sharing contribution in arriving at QBI but not the defined benefit contribution. Perhaps Lacerte is doing this because the DB contribution calculation is not based solely on Schedule C income but takes into account other factors such as age and DB account balance. I have not found any definitive guidance on this in any income tax regulation, IRS guidance, etc.