Proposed vs. Final Regulations
The preamble to the Section 199A final regs gives the option of using the proposed regs for 2018 tax returns (all final or all proposed, no cherry-picking). The proposed regs did not contain the provisions about reducing QBI by one-half of SE tax, SE health insurance, and SE retirement plan contribtions. Ror 2018 returns, is it legitimate to use the proposed regs and not make those reductions to QBI?
