The standard domestic letter rate will increase to 72c
The price of posting a letter is to increase from next month.
An Post says the move follows a pricing review by the group, and will see rates change from Thursday July 21st.
The standard domestic letter rate for items up to 100g within Ireland will increase from 70c to 72c - while the standard international letter rate up to 100g will increase from €1.05 to €1.10.
An Post says its rates will remain among the lowest in the EU 15 countries including Britain, Germany, Belgium and the Netherlands - and well below the EU domestic average of 93c.
It adds that a wide range of discount options continue to be available to businesses and "significant discount options" continue for Ceadúnas licence and bulk-mail services.
The new Ceadúnas rate for standard post letters up to 100g will be €0.70.
The company says the "significant cost" of supporting An Post's Universal Service Obligation (USO) will require attention.
The USO requires An Post to provide daily collection and delivery service to all areas of the country for a uniform tariff.
In 2015, the cost of maintaining the USO was €32.3m.
"An Post is committed to providing excellent value for money, serving Irish business and being the trusted service provider of choice for business and personal customers", a spokesperson said.