They claim the Department of Social Protection is effectively trying to shut them down.
The Irish Postmasters' Union says it contacted the Department three weeks ago, when the union became aware of the decision to transfer payments to jobseekers who work on a part-time or casual basis from post offices to banks.
IPU General Secretary Ned O'Hara, says as well as the impact on post offices, social welfare claimants are having choice taken away from them.
