Total tax revenue accrued from micro and small sized businesses combined was estimated to be approximately £120 billion in 2016/17. An estimate for 2017/18 will not become available until Autumn 2019.
The estimate given includes Self-Assessment Income Tax and Class 4 National Insurance Contributions (NICs), Corporation Tax, VAT, and Pay As You Earn Income Tax and Class 1 NICs. The definition of micro and small sized businesses used is consistent with the EU definition where possible. HMRC works to collect tax due under UK law from all businesses, regardless of size, in the most cost effective way.
The government has also taken a number of steps which benefit small businesses through the tax system. Since Budget 2016 the government has announced reductions to business rates worth more than £13bn over the next five years. NICs bills are also reduced by up to £3,000 for over one million employers, and the UK is also highly competitive, with the lowest overall corporation tax rate in the G20 at 19%. The rate is legislated to fall further to 17% in 2020.