Hello.  My elderly mother lives in my home and meets the criteria for a qualifying relative dependent on my taxes.  She receives only her social security and a very small pension that's about half of the $4200 threshold for me to claim her.  I pay all of the rent and utilities at our home.  

My question is, should I claim her and she then cannot claim herself, will I put her in the position of having to pay taxes?  As it has stood for the past several years she has had no tax liability.  I am worried that if I claim her and she cannot take the personal exemption she will have to pay tax.  

Help?