Twitter CEO Jack Dorsey has complained about a proposed tax to support the homeless in San Francisco, arguing that it is unfairly structured.

In a tweetstorm fired off on Friday, Dorsey argued that the new taxes under Proposition C would disproportionately hit Square, the payment processing company he also leads.

It followed Salesforce CEO Marc Benioff, who has a net worth of $6.2 billion, bashing Dorsey in an interview for 'hoarding' his own $5.3 billion fortune.

The measure, which is up for a vote on November 6, seeks to raise up to $300 million to support homeless services by imposing a 0.175 per cent to 0.69 per cent tax on gross receipts for businesses with over $50 million in gross annual receipts.

Twitter CEO Jack Dorsey (above) has complained about a proposed tax to support the homeless in San Francisco, arguing that it is unfairly structured

Salesforce CEO Marc Benioff (above), who has a net worth of $6.2 billion, bashed Dorsey in an interview for 'hoarding' his own $5.3 billion fortune

Homeless people hang out on the sidewalk in the Mission district in San Francisco in April. The city has roughly 7,500 homeless and a new corporate tax is on the ballot in November

'I admit that while I come at this as a citizen first, there's an unfairness I see in my role of CEO of Square (this does not apply to Twitter),' Dorsey wrote in a tweet.

'Companies like Square and Stripe would be taxed at a significantly larger total contribution than much larger companies like Salesforce,' he continued.

'Hypothetically Square could pay over $20m more in 2019, while Salesforce (4x bigger than Sq) pays less than $10m. Taxes would grow at rates multiple times our adj. revenue, which no company can sustain,' Dorsey wrote.

Square would be impacted because its net revenue, taxable under the scheme, includes fees which the company splits with banks and payment networks such as Visa and MasterCard.

In the second quarter, the company's net revenue was $815 million - more than double its adjusted revenue of $385 million, which strips out the fees that pass to partners.

Dorsey argued that much larger companies such as Salesforce, which sells subscriptions to business software, would end up paying proportionally far less of their adjusted revenue, due to the different structure of their business.

Homelessness is on the rise in San Francisco, irking residents and bringing the problem under a spotlight as a proposed tax to support homeless services is under debate

Salesforce CEO Benioff has been a vocal supporter of the new tax, and has even bashed Dorsey over his reservations.

'He just doesn't want to give, that's all. And he hasn't given anything of consequence in the city,' Benioff said of Dorsey to the Guardian.

'We have 70 billionaires in San Francisco. Not all of them are giving money away. A lot of them are just hoarding it,' Benioff said.

'This is a critical moment where I think Prop C kind of illuminates who is willing to be a San Franciscan and actually support our local services,' he added.

Dorsey included in his tweetstorm what appeared to be a veiled threat to leave San Francisco if Prop C passes.

'We're happy to pay our taxes. We just want to be treated fairly with respect to our peer companies,' he said.

'Otherwise we don't know how to practically grow in the city. That's heartbreaking for us as we love SF and want to continue to help build it.'

San Francisco mayor London Breed has opposed the new tax, saying the measure is 'well intentioned' but lacks proper controls to ensure the funds raised are properly spent.

San Francisco has about 7,500 homeless people on the streets on any given night.

Earlier this year, a United Nations official passing through the city compared conditions for the homeless there to those in a third world country.