Spain's official unemployment rate fell from 26.03 percent to 25.77 percent in one fell swoop on Thursday.
The sudden drop came after the national statistics institute (INE) revised its formulas to include data from the 2011 national census.
Spain's official unemployment rate is based on a survey of 65,000 households across the country, known as the EPA, or Active Population Survey.
The EPA is considered the clearest picture of unemployment in the country as it also captures people who are looking for work, but are not registered at the country's employment offices.
Up to now, the survey has been based on 2001 census data. But the INE has now applied 2011 census data retroactively to jobless figures from 2002 on.
The new figures also raises the number of 'active' people in Spain by 416,400 people to 23,070,900. The number of people working, meanwhile, has also climbed by 377,000 people to 17,135,200 people.
The revised numbers also show Spain's hit a peak of 26.94 in the first three months of 2013.
The lowest rate came of 7.93 percent came in the 2007's second quarter, or just before the country's building bubble burst.
The former series of jobless figures — based on the older census — will remain available on the INE site as a reference tool, the agency said.