Postmasters are to hold an emergency meeting next week to consider a ballot on industrial action.
The Irish Postmasters' Union says it comes amid mounting frustration with An Post and the Government on a range of issues.
The IPU said members are still waiting for a promised "fit for purpose" payments system following the signing of a new contract in 2018.
The union claims that payments for additional work on money laundering have not been delivered and that additional pay for 2021 Christmas payments has been withheld.
The IPU is also raising concerns over additional agency banking services, Western Union transactions as well as changes to postal money order and foreign exchange services.
The emergency meeting will be held next Monday, 28 March.
"This Meeting has been called to recognise and address low morale amongst Postmasters after enormous efforts throughout COVID-19 when our members worked longer hours, completed additional training and have been highly flexible," said IPU General Secretary Ned O’Hara.
An Post said it was disappointed that the Irish Postmasters Union is considering this current course of action.
"An Post appreciates the hard work and commitment of postmasters in the face of incredible business pressures," a spokesperson said.
"In recent times the value of the network and the work of postmasters has been a key part of the national response to Covid-19."
An Post said that in supporting postmasters it has put together a total package of €60m in financial supports and that a further pandemic relief fund of €8.5m was made available.
"An Post has been engaging, and continues to engage, with postmasters and government stakeholders to ensure the financial stability of the post office network," the spokesperson said.
