One of the biggest challenges facing the church is to retain the registered, tax-paying members (regardless of how often they attend services) to fund parishes and church agencies, especially its international relief organizations like Adveniat. German Catholics, however, are divided over the issue of a compulsory Church tax. Under the tax an additional 8 percent to 9 percent of personal income tax is deducted at source by the German state from registered churchgoers (of Catholic and Protestant communities). Although the tax provides the Catholic and Lutheran churches with an exact membership count and a net income of 5.6 billion euros (in 2008) which has helped make the German Catholic Church one of the wealthiest in the world.