IF a file is provided in which one wants the XY coordinate in attribute, first step is to be sure in what projection it is. Whichever projection, coordinate of same will be added.
This is single step process.
1.open the point layer. Goto> Vector>Add co-ordinate to points
2. Select the point layer and give save output. You can save as temporary file too.Also if you want to run many files as batch, you can select that feature too.
The output file will have XY coordinate in attribute table.