In September 2023 the Belgian treasury offered a one year state note directly to retail savers, with the withholding tax on the coupon cut to fifteen percent from the usual thirty. Households subscribed for roughly 22 billion euros, by a wide margin the largest retail debt operation in the country's history and a figure far beyond what the treasury had planned for.
The mechanics were simple, which is why it worked. Rates had risen sharply, Belgian banks had been slow to pass that through to savings accounts, and the state offered an alternative that was easy to buy, safe in the way sovereign paper is safe, and taxed more lightly. Money left deposit accounts in a matter of days.
That was not an accidental side effect. Ministers had said publicly that they wanted banks to raise the rates they paid savers, and the note was the instrument that made the point without regulation. Faced with visible outflows, several banks improved their savings offers. A funding exercise had done the work of a competition intervention, and did it faster than a regulator could have.
The cost side deserves equal attention. Retail funding at that scale is expensive relative to what the treasury pays institutional investors, and a one year instrument has to be refinanced almost immediately, which turns a single popular operation into a recurring problem. Subsequent issues raised far less, which is what happens once banks have adjusted and the tax advantage is no longer novel.
The episode left a useful piece of information behind. Belgian household savings are very large, very liquid and much more rate sensitive than the deposit market had assumed. Any institution pricing on the belief that Belgian savers do not move now has evidence to the contrary.