TASIS methodology for purging (cleansing of impure income) is unique and based on rigorous empirical research which is continuously updated. Purging involves calculation of that pro rata share of the impure (interest) income earned by a company which is the responsibility of an investor of that company. The amount thus calculated has to be donated to charity either by the investor himself or his investment agent. Purging service of TASIS is a unique and extremely valuable contribution to ensuring greater Shariah compliance by the common investor.