In Canberra, 189 small businesses were targeted earlier this year in an operation to crack down on those thought to be using cash to avoid paying their fair share of tax.

Meanwhile, new Australian Taxation Office data shows about one in three of the biggest businesses in Australia paid no tax in the 2015-16 financial year.

Small businesses in Civic, Dickson, Braddon, Manuka and Kingston were visited by the ATO in February and March this year over concerns they were using cash to avoid tax and superannuation obligations.

Of the 189 small businesses, the ATO said they will take further action with 75 and audit 22.

The breaches the ATO discovered included paying staff cash on Sundays to avoid paying penalty rates, businesses not recording transactions so as not to report income or only providing EFTPOS on certain days.

In some cases, the businesses' turnover determines rent, which meant some businesses were allowed to avoid paying rent.

Australia-wide, of the 2044 companies with profits of $100 million or more, 732 didn't pay tax. The data was released as the country celebrated new same-sex marriage laws on Thursday.

Some of the biggest offenders at the top end of town included Adani Minerals, Bluescope Steel, Atlassian, Foxtel, Origin Energy, ExxonMobil and Glencore Investment.

Others paid relatively small tax compared to profits. Despite a taxable income of over $14 billion, RTPDS Aus Pty Ltd., an entity owned by mining giant Rio Tinto, received a $6,375 tax bill. This means the company paid $1 in tax for every $2.2 million in taxable income.

Small business ombudsman Kate Carnell said while small businesses should be conducting themselves legally she agreed big business needed to pay its share.

"Small businesses often say to us, 'What about big business?'," Ms Carnell said.

"Everybody should be paying for their fair share and that would take more pressure off the economy."

She said by meeting their tax and superannuation obligations, small businesses made a level playing field for other small businesses.

"It's not fair on the businesses doing the right thing," Ms Carnell said.

She had received complaints from businesses who said competitors were "cash only" or paying staff in cash, allowing them to offer cheaper prices, which sent the message to others they had to do the wrong thing to compete.

"If everyone did that we wouldn't have any schools or road or hospitals," she said.

"Doing the right thing has got to be the easier way of operating."

Shadow assistant treasurer and Fenner MP Andrew Leigh said the tax figures released on Thursday showed the government needed to make the tax system fairer.

"Of course everyone should obey the law, but the real problem for Australia is multinational tax avoidance and tax havens," Mr Leigh said.

"They've [the government] spent more on spruiking their laws than their legislation has directly raised."

Canberra Business Chamber chief executive Robyn Hendry said her organisation could offer advice to local small businesses hoping to meet their obligations.

"I do know that at times businesses have failed to meet all their obligations by mistake," she said.

Ms Hendry said businesses which failed to meet legal and regulatory obligations undermined the fundamental premise of fair competition.

She said small businesses needed to look after their employees by doing the right thing.