You ask about the applicability of the law of
Ḥuqúqu’lláh to the money that a believer spends on
“travelling for the Faith, living a little more generously” and so
forth. Our impression from answers given to other questions is that
this is a matter for the conscience of the individual. There is, in
fact, a vast range of expenditures which could, or could not, be
included under the heading of normal annual expenses which are to be set
against income before arriving at the sum assessable to
Ḥuqúqu’lláh. In the specific case of contributions to
the various funds of the Faith, the Universal House of Justice has
already stated that it is for the individual to decide whether he will
consider these as part of his normal expenditure or will pay them out of
his savings which have been cleared.
(14 February 1993, memorandum from the Universal House of Justice to the Office of Ḥuqúqu’lláh in the Holy Land)