The Revenue Office has named 103 sites across the city, mostly houses and units but also a handful of business addresses, on which their owners owe at least a year's worth of rates or land tax.

But a property owners' group says the "naming and shaming" is unnecessary, and warns it may breach privacy laws.

Revenue Commissioner Kim Salisbury began the blitz in February by identifying a small number of addresses that were deep in arrears, and added more in March and April.

He has now significantly expanded the controversial campaign, doubling the list's size last week by adding another 47 properties.

The identified addresses are all investment properties. The tenants are not responsible for the debts.

Mr Salisbury says he is targeting only those landlords who persistently refuse to pay tax. He says the latest 47 properties have accrued debts of $339,000, or about $7200 each.

He confirms his office will apply to sell the sites if the debts are not cleared within 12 months.

"The sale-of-land program for outstanding rates and land tax on investment properties will become a regular component of our debt-recovery program."

But ACT Ratepayers and Property Owners' Association president Peter Jansen said the legislation that allowed the Revenue Commissioner to name the sites was written years ago and was "no longer compatible with contemporary attitudes towards privacy".

"We have much stronger rights to privacy today than we used to back when this legislation was written," Mr Jansen said. "I believe this campaign breaches [federal] privacy laws."

Mr Jansen said he wanted the federal Privacy Commissioner or a court to rule on the legality of Mr Salisbury's actions.

"But putting the legal question aside, there's also the matter of whether this is appropriate and necessary. Why can't he just warn the owners?"

Before this year, Mr Salisbury had never invoked his power to identify properties in tax debt, a power that had been used only twice since self-government.

ACT legislation allows the Revenue Commissioner to name housing and land for which rates and land taxes are more than a year in arrears.

If the owners haven't cleared the debt a year after the property is named, the government can apply to take over and sell the property.

Mr Salisbury said in April his campaign appeared to be working, but he would not say last week how many properties on the list were now debt-free.

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