It would make sense to refuse a raise when it pushes your effective marginal 'tax' (including reduced benefits) above 100%. The working poor (family of 4, 20K-40K in the US) often face marginal rates above 100% when you consider the phase out of various government benefits (EITC, insurance, housing,etc.) You can see the research here:

http://taxprof.typepad.com/taxprof_blog/2009/11/jacobson-100-implicit-.html and here http://mises.org/daily/3822

It would make sense to refuse a raise when it pushes your effective marginal 'tax' (including reduced benefits) above 100%. The working poor (family of 4, 20K-40K in the US) often face marginal rates above 100% when you consider the phase out of various government benefits (EITC, insurance, housing,etc.) You can see the research here and here.