Twelfth house is the house of losses and confinement. According to Bhrigu Samhita, Saturn is the natural lord of twelfth house. If you seek materialistic pleasures then Ketu in twelfth house is a bad scenaro but if you seek spiritual progress then Ketu in twelfth house is a gift from heavens.

     Twelfth house deals with losses both personal and financial, confinements and prison sentences, spiritual awakening and also higher learning like Phd. and research studies. But most important of them all its the house of moksha. Moksha is liberation from cycle of life and death. And Ketu is the only planet apart from Jupiter who can help achiece moksha via spiritual awakening. This one quality almost absolves all the bad impacts of having Ketu in twelfth house of losses. Ofcourse Ketu has to be strong for this event to happen. Still spiritual progress is guaranteed even if moksha remains unattained.

     Ofcourse for those seeking materialistic lifestyle the picture is not that rosy. Ketu could give personal or financial losses as part of its mandate to evoke spiritual awakening. Twelfth house is also the house of sex and bedroom pleasures. Having Ketu in twelfth house presents a troubling picture for marriage and sex life. This holds especially true if fiery planets like Mars and Sun are co-tenants. Its also possible if Venus is co-tenant with Ketu. Higher learning like Phd. and research studies are almost unlikely as Ketu and aspect of Rahu won't let a person focus. Unless other planets help this scenario seems to hold true. Prison sentence is a possibility in some cases especially if Saturn is a co-tenant or if Ketu is in bad sign.

     With Ketu in twelfth house there will be Rahu in sixth house. And this is the main problem. Rahu in the house of debt and disease and overlooking tenth house of career and second house of savings means native may require to earn via unethical and sometimes illegal means. And this is what presents the chance to go to prison. Also Rahu in sixth house of disease means a person can get diseases which are hard to predict without adequate tests and hospital stays. This in turn affects the savings and causes financial losses. Ofcourse native could also lose savings in philantrophic activities mostly related to medical field. Bill Gates and Mark Zuckerberg both have Ketu in twelfth house and one can see how they both are supporters of advancement in medical field.

     Ketu in twelfth house should give losses either physical or financial. There can also be problems in marriage and sex life. There is also a chance of prison stay especially if native is involved in an unethical career. But there is a bright side also. That is spiritual progress and chance of attaining moksha. Native is likely to be kind and involved in philantrophic activity so its safe to say he/she would be an asset to the world.