Analysis. If only one plan covering the Calloways includes a COB provision, then the plan without the COB provision is considered the primary provider of benefits for both Lori and Tom. Alternatively, if both plans contain a COB provision, then Lori's primary provider is her employer's plan, and her secondary provider is the plan provided by Tom's employer. Tom's primary provider is his employer's plan, and his secondary provider is the plan provided by Lori's employer