Solicitors involved in making copyright claims keep about 40% of the payments made by alleged filesharers, research shows

ACS:Law, the controversial London-based solicitors' firm involved in making copyright claims, keeps about 40% of the payments made by alleged filesharers, while rights holders receive between 20% and 30%, research by the Guardian has revealed.

For a typical letter demanding £300 as settlement for the allegation of filesharing, the record company would get between £60 and £90, while ACS:Law would retain £120. The rest would go to pay the companies which find the alleged filesharers, and to pay internet service providers to hand over data.

According to figures leaked online, and information from industry sources, approximately 10% of net revenue that comes from people who pay on receiving the letters is paid to the company that tracks down the IP addresses of suspected illicit filesharers.

A further 15% is paid to the internet service providers for retrieving the data, following a court order, detailing the names and addresses of the people implicated by the IP addresses collected through the tracking software.

A leaked business plan from the German copyright-tracking company DigiRights Solutions, used by ACS:Law and anti-piracy solicitors Gallant Macmillan, reveals that about 20% of money accrued from damages is given to copyright holders, while the law firm keeps about 80%, from which it would have to pay ISPs and IP-tracking companies.

Sources familiar with copyright infringement cases confirmed to the Guardian that rights holders can expect to receive a significant chunk – about a third – of the damages accrued from pursuing those accused of sharing copyrighted content.

From the first half of 2011, the plan says, rights holders will be forced to pay 75% of the costs of notifying and pursuing illegal downloaders, while internet service providers will foot the remaining 25% of the bill.

ACS:Law said that nobody was available to comment on the matter.

Many of the letters sent out by ACS:Law pertain to Cascada's Evacuate the Dancefloor single, produced by Allan Eshuijs, Manuel Reuter and Yann Peifer, whose Germany-based record label, Zooland Records, owns the copyright. When contacted by the Guardian, a spokesman for Zooland Records said the company had been instructed not to talk about copyright or ACS:Law by its "bosses".

Another ACS:Law client, Media CAT, did not return telephone calls or emails when contacted.

Other reports show that ACS:Law can expect a higher proportion of the sums paid against letters sent out from those accused of downloading adult material. Last week's data leak implicated 5,000 UK broadband users as having downloaded or uploaded pornography.

ACS:Law has become embroiled in a huge row over copyright infringement and online privacy in the past fortnight. It drew the ire of online forums for its method of tracking and pursuing Britons accused of infringing copyright by sharing tracks using filesharing systems. That resulted in a coordinated attack on the company's website; subsequently, the personal details of thousands of UK broadband users as well as emails belonging to ACS:Law leaked onto the site. The information commissioner is investigating whether the data leak was ACS:Law's responsibility; if it is, the firm could be liable for a fine of up to £500,000.

ACS:Law typically sends thousands of letters to UK broadband users, alleging they have infringed copyright and demanding the immediate payment of damages of £300 to £500. Reports of a business plan drawn up by the company – and later leaked online – show that the company can expect to recoup hundreds of thousands of pounds from sending out thousands of letters of this nature.

On Monday the high court granted BT an adjournment to a court order in which Gallant Macmillan, acting on behalf of Ministry of Sound, were applying for the contact details of BT-owned Plusnet broadband customers over accusations of filesharing. The Soho-based law firm suspects the customers of having illegally sharing copyrighted content.

BT further called for a moratorium on this specific legal action, which obliges the ISP to hand over customer information to the law firm which then uses the details to kickstart legal proceedings.

Neither ACS:Law or Gallant Macmillan has taken one of the copyright infringement cases to court where the proceedings have been opposed to date.