As far as income tax is concerned that individual income tax file is suitable and most acceptable method in global. Personal income tax rate is based on the individual person and even partnership is filling with the individual tax return.

You might consider looking at the joint taxation in the U.S., where it is an option. Two issues come to mind: 1) where a taxpayer filing jointly wishes to later file separately (often because they find information indicating that their spouse cannot be trusted and they are otherwise liable for the untrusted spouse's taxes), and 2) the legal history as to why Wisconsin became a "community property' State. The second issues ties to the marginal taxes paid in a progressive system when the second spouse works. In the U.S., community v. non-community property interacts with decisions to file jointly v. separately, I think.

Maintenance of privacy is important though you are double as far as the taxation is concerned.