A plain government bond has fixed coupons: 3% on €1,000 is €30 a year, done. An inflation-linked bond doesn’t: its coupon is revalued every day. Knowing how much you actually received isn’t a multiplication — which is why almost no tracker gets it right.
1. Why the coupon can’t be guessed «by eye»
A linker’s coupon is revalued for inflation through an indexation coefficient that changes every day. So the coupon that lands in your account isn’t a round number: it’s rate × coefficient-of-the-day. And that coefficient appears nowhere on your statement. Redoing it by hand, for every payment, is impractical — so most apps either skip it or estimate it roughly.
2. How we compute it: from the official figure, not an estimate
We don’t estimate. We take the official indexation coefficient published by each country’s debt agency — MEF (Italy), AFT (France), Finanzagentur (Germany), Tesoro Público (Spain) — and compute the coupon with the same convention they use: the international ICMA Actual/Actual standard, which also handles the «short» and «long» first coupons correctly. The result matches to the cent what you actually received.
3. Five families, two indices, one method
We cover 41 bonds. Almost all are linked to euro-area inflation; French OATi are the exception, tracking French consumer prices. Different indices, one method: the agency’s official figure.
| Family | Country | Index | Official source |
|---|---|---|---|
| BTP€i | Italy | Euro-area inflation | MEF |
| OAT€i | France | Euro-area inflation | AFT |
| Bund€i | Germany | Euro-area inflation | Finanzagentur |
| Inflation-linked Obligaciones | Spain | Euro-area inflation | Tesoro Público |
| OATi | France | French inflation | AFT |
4. What you see in Rebalix
Rebalix shows the past coupons of your linkers at the exact amount, tagged «from the official coefficient», with the net based on your tax residence — ready to confirm as income, so they feed your real return. And they update themselves at every new coupon, with nothing for you to do.