The IRS knows:

https://www.irs.gov/publications/p571

You can’t set up your own 403(b) account. Only employers can set up 403(b) accounts. A self-employed minister can’t set up a 403(b) account for his or her benefit. If you are a self-employed minister, only the organization (denomination) with which you are associated can set up an account for your benefit.

Do I Report Contributions on My Tax Return?

Generally, you don’t report contributions to your 403(b) account (except Roth contributions) on your tax return. Your employer will report contributions on your 2021 Form W-2. Elective deferrals will be shown in box 12 with code E for pre-tax amounts and code BB for Roth amounts, and the Retirement plan box will be checked in box 13. If you are a self-employed minister or chaplain, see the discussions next.