Theresa May will set out plans aimed at cracking down on City fat cats and tax dodgers as part of a drive to improve corporate responsibility.
Mrs May stressed that firms had a duty to pay taxes in order to fund the infrastructure and services they use.
She said that proposals examining the “whole issue of corporate behaviour” will be produced later this year.
The Prime Minister’s intervention follows the European Union case against Apple over its tax deal in Ireland and builds on themes set out during the short-lived Tory leadership contest.
When she made her pitch for the Tory leadership, Mrs May used a speech in Birmingham to set out a series of plans to rein in executive pay and bonuses, put workers into the boardroom and tackle market abuses by banks and utility companies.
She told reporters travelling with her at the G20 summit: “As you probably know if you heard that Birmingham speech I gave at the beginning of what was going to be a national leadership campaign for the Conservative Party, I was very clear that we want to look at the whole issue of corporate behaviour and we’ll be bringing out some proposals later in the year in relation to this.
“And I gave a very clear message in that speech that actually there is an issue in corporations paying taxes.
"There is a responsibility in paying taxes. Because their employees - their children are at schools, they use the health service, they use...the goods are transported by roads and trains and so forth. So it’s not that companies have no responsibility.”
She added that one of the issues she was concerned with was chief executives’ pay as a multiple of the pay of average workers.
Mrs May has sought to use the G20 summit to position the UK as a “global leader” for free trade.
But she warned that world leaders could not ignore the “anti-globalisation” sentiment that exists in many countries.
She said they needed to make sure that any free trade arrangements put in place are “actually going to benefit everybody”.
“That’s why I’m clear that we want a country that works for everyone, a government that works for everyone,” she said.
“That means the economy that works for everyone.”
Mrs May used the first session of the G20 summit to raise her concerns about the need for globalisation to benefit everybody and warned that "unless we respond to that soon trust would erode", a Number 10 official said.