IRC Section 412 clearly states it applies to 401(a) and 403(a) plans, appearing to exclude TSAs from coverage. The TSA Answer Book says they are subject to the rules.Per a discussion with Rosamund Ferber, Senior Tax Law Specialist, IRS, they may be subject under Title I of ERISA. I have review Title I, and honestly can't find a clear cut answer one way or the other. Can someone steer me in the right direction?

412 does not apply.

ERISA Title I may apply. See 29 CFR 2510.3-2(f). Also very helpful is the new DOL interpretive bulletin on whether Title I applies to payroll deduction IRAs. There also is DOL guidance on whether participation in the IRS amnesty program for 403(B) plans subjects the plan to Title I (generally no) and whether allowing hardship withdrawals subjects the plan to Title I (yes). Limiting employee contributions to the 415 limit or the exclusion allowance could subject the plan to Title I. The basic guidelines are that the plan is subject to Title I if employer-funded contributions are made or if there is excessive employer involvement with the plan. A governmental 403(B) would not be subject to Title I. This is a tricky area. You may want to hire a good employee benefits attorney.