TP is a professor with W2 and Sch C income.  Employment contract limits his moonlighting income.

In 2021, Employer exercises the claw-back provisions and claims $300K of back payment from TP for 2012 thru 2020.      

Tax law allows either a Sch A misc deduction OR a credit (based on the year-to-year differences between As-filed-and-paid and What-if).

Section 1341:  

(5)(B)......[related to the credit computation]

For purposes of paragraph (5)(B), the corresponding provisions of the Internal Revenue Code of 1939 shall be chapter 1 of such code (other than subchapter E, relating to self-employment income) and subchapter E of chapter 2 of such code.

I'm old but not old enough to remember IRC of 1939.  The clause seemed to exclude certain elements related to Self Employment Income (Chapter 1, subchapter E) and include Chapter 2 and Subchapter E, whatever it is.

Regs 1-1341 parrots the two sections without explaining it.  "Self-employment income" or "SE tax" is NOT found in the text.

I downloaded 

UNITED STATES
STATUTES AT LARGE
CONTAINING THE
LAWS AND CONCURRENT RESOLUTIONS
ENACTED DURING THE FIRST SESSION OF THE
SEVENTY-SIXTH CONGRESS OF THE UNITED STATES OF AMERICA
1939

from the internet.

The IRC on there had Chapter 1 Subchapter A thru C; and Chapter 2 Subchapter A thru D.

NO idea what "Internal Revenue Code of 1939, chapter 1 (other than subchapter E, relating to self-employment income) and subchapter E of chapter 2 of such code" are.

Help....Community Ideas

1.  For the Claim of Right Repayment Credit under Section 1341, can the TP claim the credit for the excess Self Employment Tax on the repaid income?

2.  Do you know what "Internal Revenue Code of 1939 chapter 1, subchapter E (relating to self-employment income) and subchapter E of chapter 2 of such code" are?

(The instructions on Pub 525 and other materials discuss "Tax" without addressing the applicability to Self Employment Tax in this regard.)