I basically agree with what has been said by others in this thread - but not necessarily for the reasons given. I know the Malachi chapter is generally taken as an outline for Christian giving to the Church, but I'm not 100% convinced this is a valid application. In particualr, the equation of the local church assembly with "the storehouse" seems to me a rather spurious one. The law of tithing was, however, instituted to provide for the Levites ministering in the temple, who had no tribal lands in the allocation of Israeli territory. Thus, if we are to employ the tithing principle, the funds thus 'dedicated to the Lord' are clearly to be allocated to providing salaries for those in full-time ministry, and for 'the work of His house'.
Ceretainly, there are New Testament scriptures which establish the principle of those receiving ministry providing material support for those who minister to them - 'the labourer is worthy of his hire', 'do not muzzle the ox' etc. And, logically speaking, the place where one is mainly ministered to is the local congregation of which one is part. However, there are also travelling evangelists and missionaries who are in need of support from those other than the local congregations where they are working. Some of these are funded directly by the sending congregation, but many, in this day and age, rely upon a central missionary society or some other 'para-church organisation'. Yet they are still doing 'the work of His house', and, I would say, it is therefore valid for a proportion of our 'tithe' to be dedicated to such causes. Although, I would say, our first responsibility must be to support the work of the fellowhip to which we belong - many of whom in turn 'tithe' their income to missionary causes. And, of course, in many larger denominations, a proportion of the local congregation's giving is channelled into the central organisation, to pay the wages of bishops, superintendents and regional/national administration etc.
Personally, I have always tithed, as a minimum guideline, (before tax) into my local church's coffers - currently this is divided between the two local congregations which I attend, proportionate to the extent of my involvement with each. The UK government enables me to run a 'charities account' for this purpose, where 28% of this giving is returned to me - which I channel into missions and other non-local ministry. I then give a regular planned amount (currently roughly equivalent to 6% of my disposable income) to other causes - humanitarian aid and other charities - over and above the 10% level. Any overtime I may earn tends to be subject to a much higher 'rate' of giving! And from time to time I also give additionally to particular appeals and causes 'as the Sprit leads'.
Anthony