Perhaps you should try some spelling variations:
"negative income tax" » "negativo income tax", "negativa income tax", "negativos income tax", "negative income taxi"
"negative income taxes" » "negativo income taxes", "negativa income taxes", "negativos income taxes", "negative income taxies", "negative income tales", "negative income takes", "negative income taxel", "negative income taves", "negative income tages"
"negative income axes" » "negativo income axes", "negativa income axes", "negativos income axes", "negative income axel", "negative income aves", "negative income ages"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"negative income tax\") OR (((\"negative income taxes\") OR (\"negative income axes\"))))~".
• Removing quotes may allow a broader search: (( negative income tax ) OR ((( negative income taxes ) OR ( negative income axes ))))~.
• Adding a wildcard symbol may retrieve word variants: (("negative income tax") OR ((("negative income taxes") OR ("negative income axes"))))*.