Calculation Methodology — Ireland
Detailed technical explanation of the financial principles and mathematical logic applied across our Irish State Savings simulators.
1. General Principles
- Official NTMA Data: All calculation parameters rely directly on official bonus terms and AER rates published by the National Treasury Management Agency (NTMA) for State Savings.
- Cumulative Bonus Structure: Irish State Savings products (Savings Certificates, Savings Bonds, National Solidarity Bonds) pay cumulative tax-free bonuses upon maturity or at specific annual milestones.
- DIRT Tax Exemption (0% Tax): Under Irish tax law, all returns on official State Savings products are 100% exempt from Deposit Interest Retention Tax (DIRT), PRSI, and Universal Social Charge (USC).
2. Mathematical Formulas
Total net payout at maturity is calculated as follows:
Net Payout = Principal Invested × (1 + Total Cumulative Bonus Rate)
Annual Equivalent Rate (AER) is derived as:
AER = ( (Net Payout / Principal)^(1 / Years) ) - 1
3. Indicative Nature
Results provided by our simulators are indicative estimates for decision support. Official holdings and statement values must be verified directly via State Savings / An Post.