What is the correct spelling of “dependent”? Which preposition should follow it?

Question

Dependant or dependent really confuses me when to use, especially with the combination of, on, from or to.

• Mike was dependant to/from/on his mother.
• The states are dependent to/from/on the federal government.

When to use what term with what?

Answer 1

As reported from the NOAD, dependent is both adjective and noun; dependant is used as noun in British English.

adjective
1. [ predicate] (dependent on/upon) contingent on or determined by: the various benefits will be dependent on length of service.
2. requiring someone or something for financial, emotional, or other support: an economy heavily dependent on oil exports | households with dependent children.
   • unable to do without: people dependent on drugs | welfare-dependent families.

noun ( British also dependant)
a person who relies on another, especially a family member, for financial support: a single man with no dependents.

Answer 2

The adjective derived from the verb depend is dependent, and it takes the preposition, on, just as the verb forms also take the same preposition e.g. depending on, depends on, depended on, etc. Thus, your sentences should be:

• Mike was dependent on his mother.
• The states are dependent on the federal government.

Dependent is also a noun (usually dependant in British English). When necessary, it takes the preposition of:

• Mike is still a dependant of his widowed mother.
• The states are dependents of the federal government.

Answer 3

In British English, dependant is the noun while dependent is the adjective. If X is a dependant of Y, then X is dependent on Y, meaning X depends on Y. However, in American English, dependent is used for both noun and adjective.