That which is owed; debt; that which one contracts to pay, or do, to or for another; that which belongs or may be claimed as a right; whatever custom, law, or morality requires to be done; a fee; a toll.
proper; according to accepted standards or procedures
that which is deserved or owed; "give the devil his due"
owed and payable immediately or on demand; "payment is due"
proper and appropriate; fitting; "richly deserved punishment"; "due esteem"
Currently and presently payable (e.g. many vendor invoices are due and payable upon receipt or within a stated time period).
payable, as in: The rent is due the first of every month.