29 CFR §4262.13

1. (a)In general. A plan that receives special financial assistance must be administered in accordance with the restrictions in this section and in § 4262.14.
2. (b)Restrictions and use of SFA. Special financial assistance received, and any earnings thereon—
   1. (1)May be used by the plan only to make benefit payments and pay administrative expenses;
   2. (2)Must be segregated from other plan assets as described in § 4262.14(a);
   3. (3)May be used before other plan assets are used to make benefit payments and pay administrative expenses; and
   4. (4)Must be invested in investment grade bonds or other investments as permitted by PBGC in § 4262.14.