5 CFR §894.308

1. (a)Dependency is established for a recognized natural child who lives with the enrollee in a regular parent-child relationship, a recognized natural child for whom a judicial determination of support has been obtained, or a recognized natural child to whose support the enrollee makes regular and substantial contributions.
2. (b)The following are examples of proof of regular and substantial support. More than one of the following proofs may be required to show support of a recognized natural child who does not live with the enrollee in a regular parent-child relationship and for whom a judicial determination of support has not been obtained:
   1. (1)Evidence of eligibility as a dependent child for benefits under other State or Federal programs;
   2. (2)Proof of inclusion of the child as a dependent on the enrollee's income tax returns;
   3. (3)Canceled checks, money orders, or receipts for periodic payments from the enrollee for or on behalf of the child.
   4. (4)Evidence of goods or services which show regular and substantial contributions of considerable value;
   5. (5)Any other evidence which OPM shall find to be sufficient proof of support or of paternity or maternity.