More Information On Tax Filing (Status)...

from bankrate.com/boston.com:

http://www.bankrate.com/finance/m...bill-1.asp

"In most cases, however, couples find they will generally pay more combined tax on separate returns than they would on a joint return. In some cases, at least one spouse's tax rate ends up higher than it would have been under a joint filing. Also, when a husband and wife file separate returns, they lose some tax credits and deductions they could have taken if they'd filed jointly.

Unless you are required to file separately, you should figure your tax on a joint return and on separate returns. This way you can make sure you are using the method that results in the lowest combined tax."

It seems to be a straightforward reminder.  My tax accountant usually does both (jointly and separately) to determine the best approach.