Plans to move next year's key stage 2 Sats from the second week in May to the middle of June have been cancelled.
The change, which had alarmed schools planning trips and other events, will now not take place until 2011.
The move was recommended by the expert group on assessment in its report earlier this year and accepted by ministers.
Yet a note tacked on to the bottom of a parliamentary statement on marking accuracy last week signalled a U-turn.
Vernon Coaker, schools minister, said: "I can confirm that tests in 2010 will take place as planned in the week commencing 10 May. Having taken account of QCA and Ofqual's advice, we will seek to implement the expert group's recommendation on moving the test to mid-June in 2011."
The change had been designed to prevent primary teachers from reducing their emphasis on maths and English in the second half of the summer term, leaving pupils "underprepared" for secondary school.
But heads were upset that pupils would miss out on what they believe is the most rewarding part of the year, with a more diverse curriculum.
Many schools will hope the change is abandoned altogether. The Conservatives have proposed to scrap the tests for Year 6 pupils and testing pupils when they start secondary instead.