As it stands, mayors of English strategic authorities receive most of their funding by central government grants.
Mayors are expected to start retaining some revenue from business rates from April 2027 and receive a portion of income tax from April 2028.
The rates of income tax will not change as a result of the reform.
Treasury sources say some metro mayors could end up with more money to spend if they grow their local economies and expand their tax bases, but officials are still figuring out how it will work in practice.
One think tank, Re:State, has suggested, external the government should allocate mayors 2.5p in every pound raised by the 20p basic rate of income tax in their areas.
Conservative shadow chancellor Sir Mel Stride said Burnham’s announcement was “very short on the detail” with “no new money being announced”, which could mean areas with weaker local economies could end up losing out.
The Liberal Democrats warned the plans risked “creating a postcode lottery” that would leave millions of people living in rural areas “short-changed and underfunded”.
Reform UK home affairs spokesman Zia Yusuf said the prime minister should “fully devolve the power to stop the housing of illegal migrants in local communities by the Home Office”.
The power to raise and control tax revenues is highly centralised in the UK, making the country an outlier by international standards.
The share of national taxes collected at a local level in the UK is 5.8%, the lowest in the G7, according to the OECD, external global policy forum.
That share is far below that of other countries with large economies such as France (20.4%), Japan (36%) and the US (45.7%).
During his time as Greater Manchester mayor, Burnham pushed for greater control over tax revenue, rather than having to rely on government grants.
The UK government had already been exploring whether a share of revenue from national taxes could be distributed to metro mayors before Burnham became prime minister.
Burnham has put devolution at the heart of his plan for government, arguing that metro mayors are best placed to boost economic growth across the country.
