The VAT Domestic Reverse Charge for Building and Construction Services has been deferred again. Originally it was October 2019, then October 2020, now 1 March 2021 (not the start of the tax year, which you may expect).
See our previous guidance on the topic
VAT – Domestic Reverse Charge for Building and Construction Services
VAT reverse charge on building and construction services
VAT reverse charge on building and construction services (2)
VAT: Building and Construction Services Reverse Charge – detailed guidance
VAT: Building and Construction Services Reverse Charge