The construction industry grew by 0.9% in January 2021.
Quarterly reports could place “additional burden” on companies.
The grant will cover 80% of average trading profits up to £7,500.
Main corporation tax rate will increase to 25% for firms with profits over £250,000.
Tax returns for 2019/20 will now be taken into account.
Sunak set out a £65 billion three-point plan to provide jobs and support.