20 Francs Spa

Spa's municipal authority issued emergency fractional currency in 1940 under the occupation's early disruption of normal banking — a practice repeated across dozens of Belgian communes when coin and small-denomination notes vanished from circulation almost overnight. These hyper-local emissions were authorised at the communal level, printed with whatever means were available locally, and typically redeemed within months, which kept survival rates low relative to issue quantities.

The official cachet is the only security measure, which tells you everything about the improvised urgency of the issue.