The cost of a stamp is set to increase by 20c from €1.65 to €1.85 on Tuesday, 3rd February, An Post has confirmed.
In an announcement this week, An Post said it is taking action to safeguard national delivery services and equal access to letter services nationwide.
A new €3.50 stamp for letters to anywhere in Europe, including Britain is being introduced, an increase of 85c.
Meanwhile, a new Rest of World stamp priced €3.95 is required to stem significant losses on this category of outgoing mail due to a 38% fall in international letters over the last three years.
According to An Post, the price changes are carefully calculated to cover the cost of providing its service to every address, taking account of wage increases for postal staff in line with national pay awards.
It also highlighted increased operating costs and letter volumes which have declined by 7% in the last 12 months and more than 50% since 2016.
It explained that a similar rate of decline is forecast for 2026.
Local councillor, Shane P O'Reilly has criticised the decision.
Speaking to Northern Sound, he said that "two wrongs don't make a right" when it comes to price hikes.
Cllr. O'Reilly said: "At the end of the day, if you are trying to encourage people to use the service, don't leave it that it is economically unviable for people to do it.
"There is something very nice about someone sitting down to send you a letter, but unfortunately its all being done on email," the councillor added.