Does TAXSIM-35 omit the §1402(a)(12) 92.35% adjustment in Additional Medicare Tax on self-employment income?

[PavelMakarchuk]

For a single filer with $600K of self-employment income (and no wages) in 2024:

	PolicyEngine	TAXSIM-35	Form 8959
Additional Medicare Tax	$3,186.90	$3,600.00	$3,186.90

TAXSIM's $3,600 appears to equal 0.009 × ($600,000 − $200,000) — the threshold applied to gross SE earnings. Form 8959 Part II instead applies the threshold to Schedule SE Part I line 6, which is gross × 0.9235 per IRC §1402(a)(12):

Line	Description	Value
4	SE income from Schedule SE line 6 (= gross × 0.9235)	$554,100
5	Threshold (single)	$200,000
6	Medicare wages from Part I line 3	$0
7	Line 5 − Line 6	$200,000
8	Line 4 − Line 7	$354,100
9	Line 8 × 0.009	$3,186.90

The 92.35% factor comes from the §1402(a)(12) 7.65% deduction from gross SE earnings, which defines "net earnings from self-employment" → "self-employment income" in §1402(b). §1401(b)(2) applies the 0.9% rate to this adjusted base, not gross earnings.

Reproduce:

```
taxsimid,year,state,mstat,page,sage,depx,pwages,swages,psemp,idtl
1,2024,0,1,40,0,0,0,0,600000,2
```

TAXSIM returns `fiitax = 172,396.13`, which equals `168,796.13` (v19) + `3,600.00` (implied Additional Medicare). The 0.9% computation ignores the 92.35% adjustment.

Question: Should TAXSIM-35 apply the §1402(a)(12) 7.65% deduction before comparing SE income to the Additional Medicare Tax threshold, as Form 8959 Part II lines 4–9 require?

References:

• IRC §1401(b)(2)
• IRC §1402(a)(12)
• Form 8959 (2024)