Philip Hammond must spell out the impact of his Budgets on the poorest and richest families in Britain, the chairman of the influential Treasury Select Committee has urged.
The Chancellor faced calls to publish an analysis of how measures in budgets hit people across the earnings range after George Osborne abandoned the practice.
Tory Treasury Select Committee chairman Andrew Tyrie urged the new Chancellor to reinstate the full distributional analysis previously used by Mr Osborne before being dropped in 2015.
Mr Tyrie said: "Since the summer Budget of July 2015, the Treasury has replaced its previously excellent budget distributional analysis series with a manifestly deficient substitute.
"The new Prime Minister is committing her Government to making Britain a country that works 'not for a privileged few, but for every one of us'.
"A high level of transparency about the effects of tax and welfare policy on households across the income distribution would seem to be a logical, perhaps essential starting point."
In his letter to Mr Hammond, the committee chairman said the new system showed the share of public expenditure received and taxes paid by households, broken down into five income groups.
But he said that was "inadequate" for a number of reasons and "cannot be used to determine the effect of Government policies on household incomes".
"The new distributional analysis does, of course, provide some information of use but it is manifestly deficient," he told Mr Hammond.
"It should be published alongside the income-based analysis, not instead of it."