It depends on your business and what kind of data you are collecting and processing.
In general, if you are collecting and processing personal data from individuals in the European Union (EU), you may need a data processing agreement (DPA) in order to comply with the EU's General Data Protection Regulation (GDPR). This is because the GDPR requires that any organization that processes personal data from individuals in the EU must have a written contract in place with any third-party service providers that process personal data on their behalf.
This contract, known as a Data Processing Agreement (DPA), sets out the rights and obligations of both parties with respect to the processing of personal data.