The troubled actress is said to have been paid to promote products among her followers on social networking website Twitter.
Lohan, 24, who is followed by more than 1.4m people on the site, posted an advert for gift cards on her account. Users who clicked on the link were taken to TaDa.com.
“We do not work directly with Lindsay, nor have any direct affiliation with her. She belongs to a promotion network, Mylikes, where TaDa publishes its sale content,' Mary Yee, VP of marketing at Shopzilla Inc, the owner of TaDa, said in a statement.
Lohan is said to have raked in between $2,985 and $10,000 by promoting products on Twitter.