However, as I understand it bonds have a equal payment each year, while the State Savings payments are loaded towards the end. Assuming any inflation rate , the real cost of Sate Savings may competitive from the NTMA perspective.
Sure, inflation is a factor. Another factor is the fact that the administration cost of State Savings products, per euro, is much higher than the admin cost of sovereign debt issuance.
There are lots of factors that just comparable deposit rates and comparable sovereign yields but these are the only 2 factors that the NTMA publically state that they take into account when making State Savings rate decisions.