A human rights group in Tatarstan has been hit with a large back tax claim on foreign grants after it helped a nongovernmental organization win a lawsuit over a similar claim by tax authorities.

Agora, a Kazan-based interregional association of Russian human rights groups, was notified by district tax officials that it owed 670,000 rubles ($22,440) in taxes for 2006, 2007 and 2008 on grants from the U.S. National Endowment for Democracy, Agora’s web site

Openinform.ru said Monday.

Under Russian law, charity donations from foreign organizations are not liable for taxes on income, Agora’s head Pavel Chikov said in a statement on the web site.

However, there is a loophole saying the foreign organizations must be on a government list of foreign charities to be able to provide nontaxable grants, Chikov said.

Agora’s lawyers helped Planet of Hopes, a social and environmental nongovernmental group, win three lawsuits demanding back taxes on grants from foreign sponsors.

Agora’s lawyers also have handled other clients whose cases pitted them against the authorities, including Lyudmila Kuzmina of Golos, an independent group monitoring elections; Novaya Gazeta’s Samara editor Sergei Kurt-Adzhiyev; and blogger Dmitry Solovyov. Agora also has represented relatives of human rights lawyer Stanislav Markelov, who was shot dead in central Moscow in January.