Is it correct that contributions (for myself) to a solo defined benefit plan (for a sole proprietorship or LLC taxed as a sole proprietorship with no employees) would NOT reduce self-employment tax? My understanding based on the Schedule C instructions is that contributions to such a plan would NOT be entered on Schedule C, line 19 (and so would NOT flow through to Schedule SE), but would instead be entered on Schedule 1, line 16 as an adjustment to income.