Streets in central Rome were closed to traffic and buses diverted ahead of a march due begin in the central Piazza del Popolo at 3pm local time.
Housing associations were due to rally on the Esquiline Hill at 4.30 pm near the interior ministry, where interior minister Angelino Alfano held a security summit on the protests with top officials.
Militants from the Fascist-inspired far-right Casa Pound movement were expected to join the truckers and other protesters including small business people, students and low-paid workers at the rally from Piazza del Popolo.
Protest organisers vowed there would be no repeat on Wednesday of violence seen in Rome and Turin last week as 'Pitchfork' protesters took to the streets during a nationwide truckers' strike over heavy taxes, high fuel costs and alleged government mismanagement.
Hundreds of students clashed with police in Rome on 12 December and threw firecrackers outside a university where government ministers were attending a conference.
On 10 December, police reinforcements were sent to Turin where a second day of action by truckers and other protesters disrupted transport and trade.
Police fired tear gas as thousands of farmers, truckers and unemployed people wrought havoc on road and rail traffic in cities across Italy on 9 December, the first day of the 'Pitchfork' protests.
The movement was originally a group of Sicilian farmers pushing for more help from the government but has grown into wider expression of discontent stoked by Italy's worst post-war recession which has lasted more than two years.
Targets range from tax collection agency Equitalia and high fuel prices to the political class, privileged elites and the single European currency.