Bizum has transformed the way instant money transfers are made in Spain. With millions of users relying on the service every day to send money, pay for online purchases or make charitable donations, the platform has become a staple of everyday financial life. However, not everything is permitted when completing a transfer. Certain words are strictly forbidden in the transaction reference, and using them can lead to blocked payments or even bank investigations.
At first glance, Bizum’s operation is simple. Users access their banking app, select the option to send money, choose a contact from their phonebook, enter the amount and add a short reference before confirming the transaction. Yet this final step, often treated as a formality, carries significant legal weight. Financial institutions are legally obliged to monitor transactions that could be linked to criminal activity or money laundering.
This obligation is rooted in Spain’s Law 10/2010 on the prevention of money laundering and the financing of terrorism, which remains in force in 2025. Under this legislation, banks must scrutinise suspicious transactions and report them to the relevant authorities when necessary. As a result, Bizum and participating banks have deployed automated detection systems that scan transaction references for specific words and expressions.
Among the terms that are completely prohibited are those linked to terrorism, weapons or violence. References to terrorist organisations, armed conflicts or firearms automatically trigger security protocols. The same applies to language associated with kidnapping or contract killing. Even when used jokingly or without criminal intent, such expressions can result in the immediate blocking of a transaction or further scrutiny by the bank.
The systems in place do not assess tone or context. Any reference flagged by the filters is treated as potentially suspicious, regardless of whether it was intended as humour. This preventive approach can lead to administrative or legal consequences for users who underestimate the importance of the reference field.
Drug trafficking is another area subject to particularly strict controls. Explicit mentions of illegal substances, slang terms or indirect references to quantities can all raise red flags. Banks apply a zero-tolerance policy in this area to prevent Bizum from being used as a payment method for narcotics-related transactions, in line with their legal obligations to combat money laundering.
Less widely known, but equally monitored, are references to human organs and tissues. Mentions of organs, corpses or irregular medical procedures are prohibited, as they may suggest illegal organ trafficking. While organ donation is legal in Spain when carried out through official medical channels, financial transfers that explicitly reference such practices can be interpreted as evidence of criminal activity, which is heavily penalised under Spanish and European law.
Direct references to money laundering itself are also banned. Expressions such as “black money” or “money to launder” immediately activate alert systems. Although it may seem unlikely that such language would be used in genuine criminal activity, automated filters cannot determine intent and will block or flag any transaction containing these terms. The system prioritises regulatory compliance and security over user convenience.
In addition, the names of individuals linked to terrorism, organised crime or serious criminal investigations may also trigger alerts. While Bizum does not disclose the full list of monitored names, these measures are designed to prevent the financing of criminal networks rather than to imply guilt. The controls do not override the presumption of innocence, but serve as preventive mechanisms established by law.
When a prohibited term is detected, the system can respond in several ways. A transaction may be automatically rejected, processed but flagged for later review, or escalated to a bank’s compliance department. In more serious cases, banks may request additional information from the customer, temporarily restrict the account or report the transaction to the authorities.
Bizum itself is an instant mobile payment system created by Spain’s leading banks in 2016. Integrated directly into mobile banking apps, it allows users to send and receive money using only a phone number, without the need for additional applications. The service has become especially popular for peer-to-peer payments, such as sharing restaurant bills or contributing to group gifts.
By 2025, Bizum has more than 28 million users in Spain and processes hundreds of millions of transactions each year, making it one of the country’s most widely used digital payment methods. Transfers between individuals are generally limited to €1,000 per transaction, with monthly caps that vary by bank but typically sit around €5,000. Higher limits may apply to payments to businesses, depending on the user’s agreement with their bank. For larger sums, banks continue to recommend traditional bank transfers, which allow higher amounts but involve longer processing times and, in some cases, additional fees.