A Belgian savings rate adds together two things that follow different rules: a base rate (taux de base), earned from the day after your deposit, and a loyalty bonus (prime de fidélité), earned only after twelve months with no withdrawal. The second is never guaranteed in advance. Over a first year, the gap between the advertised figure and the yield you actually collect often exceeds a factor of five.
Two rates inside a single advertised figure
The "3.15%" on a bank poster exists nowhere in the contract. It is the sum of two separate lines, and Wikifin, the financial education site run by the FSMA (Belgium's Financial Services and Markets Authority) spells it out: on most Belgian regulated savings accounts, the saver earns a base rate plus a loyalty bonus.
The base rate starts the day after the deposit, accrues daily, and lands once a year with value date 1 January. The bank can change it whenever it likes, on money already deposited as well as on future deposits. One constraint applies: an increase must be held for at least three months.
The loyalty bonus works the other way round. It is only earned on sums that stay in the account for twelve consecutive months, its rate is locked in on the day of the deposit, and it is paid quarterly, on 1 January, 1 April, 1 July or 1 October.
Belfius illustrates the gap better than any explanation. On its plain savings account, the rate splits into 0.30% base and 0.30% bonus, half and half. On the Belfius Fidelity account, it splits into 0.15% base and 1.50% bonus, meaning 91% of the yield hangs on a duration condition. Two accounts at the same bank, two radically different yield risk profiles.
Why does a bonus increase not reach you for twelve months?
Because the bonus rate in force on the day of the deposit stays unchanged for the whole twelve-month period that follows. An increase announced in June therefore does not apply to money deposited in January.
The Belfius press release of 12 June 2026 puts it plainly: on the Belfius Fidelity account, the bonus rises from 1.25% to 1.50% on 1 July, but "for deposits made before 30 June 2026, the old loyalty bonus still applies". The new rate only reaches earlier deposits when their next accrual period begins.
Take €20,000 deposited into that account on 15 January 2026. It went in under a 1.25% bonus. It will keep that rate until 15 January 2027, while the bank has been advertising 1.50% since 1 July. Shortfall over that period: €50 gross, for a customer who did nothing wrong and who reads a higher rate on screen.
The deposit cap decides how much capital earns the rate
Every account advertising more than 3% is an account with amount conditions attached. Belfius classes them as category B, as opposed to category A accounts with "no conditions on amounts or terms". The distinction is not cosmetic: it determines how much money can actually work at the advertised rate.
Here is the state of the market on 29 August 2026, broken down.
| Savings account | Base rate | Loyalty bonus | Advertised total | Deposit cap |
|---|---|---|---|---|
| KBC Start2Save | 1.65% | 1.50% | 3.15% | €500/month |
| Belfius Flow | 1.60% | 1.50% | 3.10% | €600/month |
| ING Épargne Tempo | 1.60% | 1.50% | 3.10% | €500/month |
| Argenta Compte d'accroissement | 1.50% | 1.50% | 3.00% | €500/month |
| Keytrade High Fidelity | 0.40% | 1.50% | 1.90% | none |
| Belfius Fidelity | 0.15% | 1.50% | 1.65% | none |
| Belfius Compte d'épargne | 0.30% | 0.30% | 0.60% | none |
KBC: base rate raised from 0.75% to 1.65% on 1 August 2026. Belfius: press release of 12 June 2026, rates effective 1 July. ING: increase effective 1 July 2026. Argenta: document dated 11 June 2026. Keytrade: key information sheet of 24 March 2026.
A savings rate is always read together with its deposit cap. The ranking flips completely depending on whether you are setting money aside every month or placing capital you already hold. Our ranking of Belgian banks carries this breakdown institution by institution.
What does €10,000 at 3.15% actually earn?
Roughly €61 gross in the first year, an effective yield of 0.61%. The calculation runs to three lines and appears on no product page.
You open a KBC Start2Save on 1 September 2026 with €10,000 to place. The cap allows €500 a month: over twelve months you can only fit €6,000 into it, and the rest sits elsewhere. Each deposit spends an average of 6.5 months in the account before its anniversary, which gives €500 × 1.65% × 6.5 deposit-years, or €53.60 of base interest. On the bonus side, a single deposit reaches its twelve months within the window, the one from September 2026: €500 × 1.50%, or €7.50, paid on 1 October 2027. Total: €61.
Reading the advertised rate naively gave €10,000 × 3.15% = €315.
The objection is fair: over the long run the account fills up and the advertised rate does materialise. That holds, with two caveats. It takes twenty months to fit €10,000 in, and more than six years for €40,000; throughout that time the bank can cut its base rate as it pleases, since only an increase is protected for three months. A boosted rate rewards a flow, not a stock.
On capital you already hold, the hierarchy reverses outright. With €40,000 in hand, a Keytrade High Fidelity account at 1.90% with no cap returns about €760 gross over twelve full months; the same money in a Start2Save at 3.15% returns €61, because the account only accepts €6,000 of it. Even a Belfius Compte d'épargne at 0.60%, four times less generous on paper, produces €240 in year one.
Four lines of the key information sheet are enough to settle it:
- The monthly deposit cap, and any cap on the total balance.
- The share of the yield carried by the loyalty bonus, the part that demands twelve months of patience.
- The date of the sheet you are reading, because Belgian rates moved four times between March and August 2026.
- Ancillary fees: Belfius, for instance, charges €1.50 plus postage for every letter it sends.
Does a withdrawal cost you the bonus on the whole account?
No, only on the sum withdrawn. The calculation rule is imposed on banks: they must treat you as withdrawing the most recently deposited sums, meaning the ones that have accumulated the fewest loyalty days.
Your oldest deposits quietly carry on with their countdown. Withdrawing €1,000 in November from an account funded for three years costs you the bonus on the youngest €1,000 only.
The 15% withholding tax above €1,020 of interest
In 2026, interest from a regulated savings account is exempt up to €1,020 per person, or €2,040 for an account held by two married or legally cohabiting partners. Above that, the withholding tax (précompte mobilier) is 15%, against 30% on a non-regulated account. The threshold stays frozen at €1,020 through income year 2030.
That ceiling is higher than most people assume. At 1.90%, you need roughly €53,700 in the account to reach it. On a boosted account capped at €500 a month, it is out of reach before year six. The exemption is calculated per taxpayer, not per account: if you hold several accounts, including at different banks and including your minor children's, adding them up and declaring the total is your job.
Which figure should you check before moving your savings?
Vocabulary carries much of the confusion. A loyalty bonus is not a commercial perk or a welcome offer: it is a regulated component of the yield, defined in the account terms, and the bank must publish its rate separately from the base rate. Nothing obliges you to do this arithmetic in your head. The key information sheet for savers carries both figures, the cap and the date; you just have to open it rather than stopping at the product page.
For a choice about the bank rather than only the account, the Belgian bank comparator sets annual costs against rates, and our article on Keytrade Keypack covers a savings account with no cap attached to a free current account. Belgian banking fees often weigh more than the rate gap: a current account at €51 a year eats the entire return on €6,000 of savings at 1%.
If you disagree with your bank about how a bonus was calculated, Ombudsfin, the Belgian ombudsman for financial disputes, handles complaints free of charge once the bank's own complaints service has been through.
Sources
- Wikifin (FSMA), What does your savings account earn you?: mechanics of the base rate and the loyalty bonus, withdrawal rule, 2026 exemption. Page updated 12 May 2026.
- Belfius, Rate changes on Belfius Flow and Belfius Fidelity: press release of 12 June 2026, 1.60% + 1.50% on Flow, 0.15% + 1.50% on Fidelity, 0.30% + 0.30% on the plain savings account, and the rule governing new bonus rates.
- Test-Achats, KBC takes the lead on savings accounts at 3.15%: 7 July 2026, base rate raised from 0.75% to 1.65% on 1 August, market deposit caps.
- Test-Achats, ING raises the Épargne Tempo rate to 3.10%: 26 June 2026.
- ING, ING increases the rates on its regulated savings accounts: 1.60% + 1.50% on Épargne Tempo from 1 July 2026.
- FPS Finance, Movable income: 15% withholding tax on the taxable share of regulated accounts, accessed 29 August 2026.
- Ombudsfin, Submit a complaint: free mediation for banking disputes, accessed 29 August 2026.
- Keytrade Bank, Key information for savers, High Fidelity account: 0.40% + 1.50%, maximum deposit not applicable, sheet dated 24 March 2026.
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Marion a travaillé six ans en agence, à Namur puis à Bruxelles, avant de passer côté rédaction en 2020. Elle a ouvert, fermé et transféré assez de comptes à vue pour savoir où se cachent les frais : le forfait « tout compris » qui exclut justement le virement instantané, la carte de crédit offerte la première année, le compte d’épargne dont la prime de fidélité s’évapore au premier retrait. Depuis, elle relit chaque janvier et chaque juillet les documents d’information tarifaire des banques belges, recalcule le coût annuel réel par profil, et vérifie ce que rapporte vraiment un taux affiché quand le plafond est de 500 € par mois. Ce qui l’agace : les comparatifs qui classent une banque première sur la qualité de son application alors que le client, lui, paie ses frais en euros.