What is the proposed basis period reform?

The change in basis periods will mean that Self-Assessment individuals and businesses will have to align their tax year with 6th April to 5th April tax year.
However, landlords’ basis period always mirror 6th April to 5th April tax year so they shouldn’t be affected.
It is expected that MTD for ITSA and the basis period change will coincide.
For more detail: HMRC basis period reform policy paper.