This study examines the effect of banking market consolidations via mergers and acquisitions (M&As) on the role of banks in intermediating corporate tax planning through offshore tax haven operations. We find that bank clients significantly increase their tax haven operations after their banks are merged with others. In addition, such an increase is greater when a commercial bank merges with an investment bank and when the clients have greater tax planning opportunities. We also employ network analyses to show that the propensity for a client to expand its operations into a new tax haven country increases significantly when its relationship bank enters into this country through an M&A. Collectively, our findings reveal that bank M&As enhance banks’ tax intermediation capability.