In April, May and June the difference was a matter of 0.1 percent, but in July came the biggest error. The bureau reported inflation for the month was at 4.4 percent when in reality it was only 4.1.
The error was picked up when Statistics Sweden were presenting their latest inflation figures.
The blunder mislead the Bank of Sweden so that they raised their interest rates last week.
Analysts say belief in the bureau has been dealt a serious blow.