TPA means Third Party Administrator and it can take on several meanings within the HR industry.

For insurance topics, a third-party administrator is a company that provides operational services such as claims processing and employee benefits management under contract to another company.

Insurance companies and self-insured companies often outsource their claims processing to third parties.
For retirement benefits, a TPA is an organization that manages many day-to-day aspects of an employee retirement plan.

A TPA performs responsibilities such as designing retirement plan documents, preparing employer and employee benefit statements, preparing employer and employee benefit statements, ensuring the plan follows the IRS non-discrimination requirements, preparing annual returns and reports required by IRS, DOL or other government agencies.

These tasks are often burdensome and time consuming for many businesses.