If you thought you could make money online without declaring it to the taxman, think again.

Austria, Denmark, Britain, Canada, The Netherlands and Sweden have teamed up for the “Xenon” program, which was started in The Netherlands in 2004 by the Dutch equivalent of the IRS, Belastingdienst.

Wired Digital reports, “Xenon is primarily a spider: a program that downloads a web page, then traverses its links and downloads those as well, ad infinitum. In this manner spiders can create huge datasets of web material, while preserving the relationships between pages at the moment they were spidered — something that can reveal a lot about the people that made the pages.”

The program aims to crack down on suspected internet tax cheats, using a sophisticated web crawling program to monitor transactions on auction sites, and track operators of online shops, poker and porn sites.

Once the web pages are screen-scraped, Xenon’s Identity Information Extraction Module interfaces with national databases containing information like street and city names. It uses that data to automatically identify mailing addresses and other identity information present on the websites it has crawled, which it puts into a database that can be matched in bulk with national tax records.

Canada’s tax authorities declined to state what its Xenon data retention policies are, as did Simon Bird, head of the “Web Robot Team” at the British HM Revenue and Customs office.

In the United States, the IRS is not a part of the Xenon project, but would neither confirm nor deny that it uses spidering software in its investigations.