What is the role of a corresponding author?
The corresponding author (CA) has an important role, taking primary responsibility for communication with the journal (through submission, peer review, revisions, proofs etc), ensuring that all co-authors agree to the contents of the manuscript (and any revisions) and that all matters comply with the policies of the journal, as well as signing the Publication Agreement and arranging payment of an article processing charge, where required.
The CA should also be available for any post-publication queries (correspondence from other members of the community, requests for materials and data, ethics queries etc). In addition, the role of CA is often seen to confer a level of seniority and experience.
The CA should ensure that all co-authors have agreed authorship and contributorship (using the CRediT taxonomy) before submission.
The choice of CA on a manuscript should be based on the above commitments rather than any financial considerations.