Emilio Botín is a billionaire Spanish banker renowned for running a tight ship. He asks that his top credit officers at Santander — one of Europe’s largest banks — make a trek to his vacation home each summer to report on loan exposures. And he queries the head of his charitable foundation, euro for euro, on its smallest donations. Enlarge This Image Daniel Ochoa De Olza/Associated Press A Spanish court is investigating whether the family of Emilio Botín, the head of Banco Santander, paid too little taxes. Add to Portfolio HSBC Holdings PLC Barclays PLC Go to your Portfolio » Enlarge This Image Nacho Cubero/Reuters Emilio Botín is head of Banco Santander, which is based in Madrid. Readers’ Comments Share your thoughts. Post a Comment » Read All Comments (30) » Yet, there is one not-so-small matter that Mr. Botín (pronounced bo-TEEN) has failed to keep tabs on: a Swiss bank account secretly opened long ago by his father that grew to such a size that when Spanish authorities discovered its existence last year, Mr. Botín and other family members paid 200 million euros (about $273 million currently) in taxes to avoid tax evasion charges. At the request of tax fraud inspectors, a Spanish national court is investigating whether the payment is enough, given the amount that was stashed abroad; tax experts in Spain say that the account could reach two billion euros. The court has also said that officials need more time to sift through the blizzard of documents that the family submitted and will consider whether a criminal charge of document fraud should be brought. A lawyer for the Botíns, Jesús Remón, said the family was cooperating with the investigation and was “fully in compliance with its tax obligations following their voluntary filing” last year. He added that no family member had been charged with wrongdoing. Mr. Botín’s tax problems come as debate intensifies over whether struggling governments should demand more tax revenue from the rich. On Monday, President Obama called to end some tax breaks for the wealthiest taxpayers in the United States. Last Friday, the Spanish government reintroduced a wealth tax that it had abolished three years earlier, hoping to collect an estimated 1.08 billion euros from taxpayers with more than 700,000 euros in declared assets. Spain’s wealthiest have so far not publicly endorsed calls for higher taxes, and Mr. Botín on Friday told reporters that “it seems to me very bad to reintroduce” the wealth tax. More so than in other European countries, where bankers are largely anonymous figures, Mr. Botín holds sway in Spain. Although he avoids social events and his public utterances are few, his influence is seen as wide-ranging. And he has been able to retain control of Santander despite his family’s controlling just 2 percent of its shares. Neither the judiciary nor the family has provided details about how much money the Swiss bank account contained or how the amount grew over time. Nor would Mr. Remón, the lawyer, comment on whether Mr. Botín had been aware of the account. What is known is that Mr. Botín’s father, also called Emilio, left Spain with part of his wealth in late 1936, after the start of the Spanish Civil War, fearing, like many other Spaniards, what might come. The elder Mr. Botín spent a few months in London before moving to Basel, Switzerland, and eventually returning to Spain to resume leadership of the bank that he had run since 1933. But while he returned to Spain, the money he salted away in Switzerland did not. The senior Botín died in 1993. Last year, the French government passed on to Spain data that it had obtained from Hervé Falciani, a former employee in HSBC’s Swiss subsidiary, naming almost 600 Spanish holders of secret bank accounts. Among those was one belonging to the estate of Mr. Botín’s father. In his opening summary, the judge in charge of the case, Fernando Andreu, highlighted “the complexity of the hereditary structures” of trusts, foundations and other companies set up to oversee the account. The closest he came to explaining what was in the account was to say that it also included a 12 percent stake in Bankinter, a midsize bank in which Jaime Botín, Emilio’s brother, is a leading shareholder. That holding, at current stock market value, would be worth about $310 million.