I do not think it is within the scope of this particular clause to start getting too much into the devolutionary settlement for Wales.
The regime was set out in the 2015 Act, which, subject to commencement regulations, will devolve corporation tax rate-setting powers to the Northern Ireland Assembly. The Government have committed to working with an incoming Northern Ireland Executive on options for commencement, including on timing and adjustments to the Northern Ireland Executive block grant to reflect tax revenues forgone by the UK Government.
There are two key features to the regime’s design. First, the devolved rate will apply only to a company’s trading profits; investment activities, which are highly mobile, are not in scope. Secondly, the Act requires large companies with a substantial trading presence in Northern Ireland to calculate their Northern Ireland profits separately from the rest of their profits. That calculation must follow internationally accepted principles for attributing cross-border profits. Broadly, that means that companies with profits generated in different tax jurisdictions must calculate their branch profits as though each branch were an independent entity. These profit attribution rules are important to make sure the regime works as intended.
An SME with 75% or more of employment time and costs in Northern Ireland would have all its trading profit taxed at the Northern Ireland corporation tax rate. An SME below the 75% threshold would have all its trading profits, including those generated in Northern Ireland, taxed at the UK corporation tax rate.