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Bond Interest Calculator 2026

Government bonds are one of the safest ways to save — returns are guaranteed by the state treasury. The bond interest calculator lets you quickly find out how much you will earn: enter the face value, annual interest rate and number of years, and the tool computes gross interest, deducts 19% capital gains tax (Belka tax) and shows the real net profit and effective annual net rate. Use the calculator to compare different bond series — from one-year to multi-year maturities — and determine which instrument best fits your financial goals. Results are rounded to the nearest grosz, reflecting the actual amounts paid by the issuer.

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How the bond interest calculator works

Step 1: Enter the face value of the bond (e.g. PLN 10,000). Step 2: Enter the annual interest rate (e.g. 6.2%). Step 3: Set the investment period in years (e.g. 1, 2, 3 years). Step 4: Gross interest = Face value × (Rate / 100) × Years. Step 5: Belka tax = Gross interest × 0.19 (19% capital gains tax). Step 6: Net interest = Gross interest − Belka tax. Step 7: Effective net rate = (Net interest / Face value / Years) × 100%. All amounts are rounded to the nearest grosz.

Example: PLN 10,000, rate 6.2%, period 1 year

Face value: PLN 10,000. Annual rate: 6.2%. Period: 1 year. Gross interest: PLN 620.00. Belka tax (19%): PLN 117.80. Net interest: PLN 502.20. Effective net rate: 5.02% per annum. For a 3-year bond at the same rate with a face value of PLN 30,000: gross interest PLN 5,580, tax PLN 1,060.20, net PLN 4,519.80.

Frequently asked questions

How does the bond interest calculator work?

Enter the face value of the bond, the annual interest rate and the number of years. The calculator computes gross interest, deducts 19% capital gains tax (Belka tax) and displays the net interest and the effective annual net rate. All amounts are rounded to the nearest grosz.

What formula does the calculator use?

Gross interest = Face value × (Rate / 100) × Years. Belka tax = Gross interest × 0.19. Net interest = Gross interest − Belka tax. Effective net rate = (Net interest / Face value / Years) × 100%.

Does the calculator include the Belka capital gains tax?

Yes. Interest income from government bonds is subject to a 19% capital gains tax in Poland (the "Belka tax"). The calculator automatically deducts this tax and shows both gross and net figures for easy comparison.

Gross interest for one year = PLN 620. Belka tax = PLN 117.80. Net interest = PLN 502.20. The effective net annual rate is 5.02%. For a 3-year bond at the same rate, the net interest totals PLN 1,506.60.

Fixed-rate bonds carry a predetermined interest rate for the entire term (e.g. 6.2% per year). Floating-rate bonds have a rate tied to an external benchmark (e.g. WIBOR or CPI inflation) and reset each interest period. The calculator works for both — just enter the current rate.

The Ministry of Finance offers: 3-month (OFL), 1-year (ROR, DOR), 2-year (DOS), 3-year (TOZ), 4-year (COI, EDO), 6-year (ROS) and 12-year (ROD) savings bonds. They differ in rate, coupon structure and early redemption terms. Enter the rate of any series into the calculator.

Government bonds are guaranteed by the state treasury and are among the safest financial instruments. In a high-interest-rate environment they offer attractive returns. Use the calculator to compare the real net yield with a bank deposit or other instruments.

The calculator multiplies the face value by the annual rate and by the number of years — this is simple interest without coupon reinvestment. To factor in compounding from reinvested coupons, use the compound interest calculator.

The calculator uses the face value and the stated rate. YTM for bonds bought at a price other than face value requires a more advanced model. For a rough estimate, you can enter the purchase price as the face value and compare results.

No. The calculator is for informational and educational purposes only. Actual interest, payment schedules and tax depend on the specific bond terms and current tax law. Consult a financial adviser before making investment decisions.

This calculator is for informational and educational purposes only. Results are approximate and do not account for individual bond terms, coupon payment schedules or potential changes in tax law. Actual interest amounts and taxes may differ depending on the specific bond product and current regulations. Before making investment decisions, consult a licensed financial or tax adviser.

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