The use of dependant and dependent is a very good example of the constant changes taking place in the English language. Fellow users of British English are probably aware of the traditional distinction.
- a person who depends on someone else for financial support
- requiring a person or thing for aid or support; unable to do without
- [dependent on] conditioned, influenced or determined by; contingent on
However, you might be surprised to learn that you can also use the spelling dependent for the noun. Dependent has recently muscled its way to the status of a standard variant spelling of dependant; dependent is now as common as dependant in the Oxford English Corpus (according to Fowler’s and the Oxford Dictionary online).
Dependent was already the standard spelling in American English. And dependent is the only standard spelling for the adjective.