The latest league tables show how more than 15,000 primary schools performed in national curriculum tests - known as SATs - in English (reading and writing) and maths.
Under the Government's current target, schools are considered failing if fewer than 60% of 11-year-olds reach the expected standard - Level 4 - in English and maths SATs tests, and fewer youngsters make two levels of progress in these subjects than the national average.
The national average for English progress this year is 92%, and for maths it is 90%.
Schools that fail to reach this threshold are at risk of being closed and turned into academies.
The latest figures show that of the 521 schools which are below the bar, 45 have already closed, with 37 becoming academies.
Stephen Twigg, Labour’s shadow education secretary, has challenged the government to make “sustainable” improvements to schools that go beyond the new academy drive announced today.
The original focus of Labour’s academy programme was on under-performing schools – but unlike this Government, we worked with schools to ensure improvements were sustainable.
Changing the type of school is not enough – we need a programme to raise the quality of teaching and school leadership, which is what makes the most difference. But under this Government, we’ve seen 10,000 teachers leave the profession.
We also need a One Nation education plan – getting strong schools to support weaker schools, so that no school is left behind. That can be achieved in many ways, including through federations, clusters of schools and co-operative trusts – academies are not the only answer.