My question is whether a clergy’s 403(b) contribution which is excluded from income should be added back for SE calculations (similar to the housing allowance).

Proseries doesn’t add it back. Another site is promoting the tremendous tax advantage of pre-income, pre-SE tax for clergy 403(b) contributions.

But, section 1402 says:
(a) Net earnings from self-employment means the gross income derived by an individual from any trade or business less the deductions allowed by this subtitle.
(a)(8) excludes both housing allowance and retirement distributions during retirement from SE tax
(a)(14) states that in the case of church employee income, the special rules of (j)(1) shall apply
(e) discusses the exemption process – doesn’t apply to this question. If a minister opts out of ss, then of course the minister would not pay se tax on 403(b) contributions.
(j)(1) – Computation of net earnings in apply subsection (a) –
(A) church employee income shall not be reduced by any deduction;
(B) church employee income and deductions attributable to such income shall not be taken into account in determining the amount of other net earnings from self-employment

Section 3121(b)(8) – doesn’t address retirement contributions

The 2017 Instructions for Schedule SE states that ministers must pay SE tax if you had church employee income of $108.28 or more. Church employee income is wages you received as an employee of a church….. – But, given the dual status of clergy, not sure I could rely on this.

I am not seeing anything in the code which specifically exempts ministers’ 403(b) contributions from the SE tax calculation. Certainly, non-clergy employees pay FICA on 401(k) contributions but no FICA on HSA contributions. Non-clergy self-employed cannot deduct retirement contributions for purposes of SE tax, correct? Conversely, the code is very clear that clergy 403(b) distributions are exempt from SE tax once the minister retires.

If clergy contributions to 403(b) are exempt from SE tax, this is indeed a tremendous tax break and I would like to educate clergy accordingly. But, I would like confirmation that it is before doing so and am not finding it yet.

If you have some research or thoughts on this, I would appreciate this. Thanks so much.