gst所有人都要交的，楼主的问题应该是你residential的电话费等是否能claim gst from ird，从accounting的角度来说，虽然你的residential part 包含在commercial lease里，但任何expense不是business上的是不能claim gst 或是expense against your business income. 税务局一般会考虑the nature of the expense。
从法律上来说，至于你能否contract out the residential part of the lease, it's pretty much depends on the lease agreement. 所以建议你把合同拿给律师看一下，你这么问，很难给一个具体的答案作者: marx 时间: 2010-9-14 17:40:46
Generally, the supply of residential property is an exempt supply, unless both you and your landlord agreed not to be treated as exempt supply. from the landlord side, they should differentiate between commecial lease & residencial lease, perhaps they have not done it properly, so LZ should rise this issue to your landlord.作者: AMICUS_LAW 时间: 2010-9-15 13:48:44