how to combine records of two Queries?

I’m designing a database calculating salary in a company. In order to make calculation, I have to design Queries.

One item in the Query is Personal Income Tax. There are two categories: for local people, Tax is (Sum minus 880), then further calculation; for foreign people, Tax is (Sum minus 4000), then same further calculation.

I’ve tried to design a IIF function, but failed. So have to make two Queries. They have exactly same items, but with different formula.

And now I need to combine the records of the two Queries. Then how to do it?

Append Query is just for table, not for existing Queries.