Sjöstrand called on the government to intervene and act to protect the integrity of individuals and their personal data.
"Let the individual decide if his or her personal data should be released," Sjöstrand wrote in an article in Dagens Nyheter on Sunday.
Sjöstrand pointed out that information requested from the tax authorities over the tax and financial affairs of private individuals can, with the help of modern technology, be made easily and widely available.
The Swedish principle of of public access to official records is being misused for financial gain, Sjöstrand writes.
"Technological advances mean that this information can be spread in a way that threatens personal integrity."
Sjöstrand wrote that the agency receives a storm of complaints annually from private individuals angry that their income and financial information is widely available at the click of a mouse over the internet.
He called on the government to act to give private individuals a say in how their information is used.
He also called for the scrutiny of firms that seek and distribute information to ensure that they follow the ethical rules that apply to credit-rating agencies and not simply to meet public curiosity over the affairs of their neighbour.
Sjöstrand concluded that the tax agency relies on its reputation and the trust of the public to conduct its work efficiently.
"Without the trust of people and companies our task becomes harder and there is a risk of the creation of an inefficient public agency that works poorly."