Protesters from all over Italy rallied in Venice as the G20 summit continued on Saturday.
It's the first face-to-face meeting between finance ministers of the world's 20 largest economies, since the global health crisis began.
With corporate tax reform at the top of the agenda, a landmark proposal to stop multinational companies from shifting profits to low-tax havens was endorsed.
That would pave the way for G20 leaders to finalise a new global minimum corporate tax rate of 15% at a Rome summit in October.
Demonstrators near the canals of Venice however, were not convinced.
"They are there discussing and taking decisions that concern everybody in the world and they are not listening to the people so we are here to tell them they cannot...twenty people discuss something that concerns everybody."
Setting a tax floor is intended to stop multinationals from setting up shop in countries with the lowest tax rate.
It would change the way that companies like Amazon and Google are taxed, basing it partly on where they sell products and services, rather than on the location of their headquarters.
The move could also recoup hundreds of billions of dollars for public treasuries under strain during the current crisis.
British Finance Minister, Rishi Sunak.
"This agreement ensures that our tax system is fit for the digital age and crucially, that the right companies pay the right tax in the right places."
A final statement from the summit said the global economic outlook saw improvement since talks in April.
However it also warned that recovery could be hampered by an upsurge in fast-spreading variants such as Delta, and inequitable distribution of vaccinations, globally.
Among some of the wealthiest countries over two-thirds of citizen have had at least one shot of vaccine.
But that figure falls well below 5% for many African nations.