The website of the Spanish Tax Office crashed on Tuesday after thousands of users rushed to be the first to apply for their 2011 tax forms.
The economic crisis has led many taxpayers owed money by the Treasury to make their applications as quickly as possible in the hope they will receive their money back immediately.
A few hours after the service was made available at midnight on Tuesday, a record 25,000 forms had been confirmed, said the organization.
But as users flooded the site, it found itself unable to cope with the 5,600 transactions a second it was receiving - the daily average is 500.
By the middle of the afternoon the site was working at 50 percent its usual capacity.