How much can you expect to get back on your taxes?

You get back however much extra you paid (through payroll witholding) during the year.

If you made $40,000 and had $10,000 withheld, and the bottom line of your 1040 says you owe $9,900 in tax, that means you paid $100 too much, so your refund would be $100.

If you follow the tax tables on the W-4 form (the one you give your work where you figure out withholding), you will usually end up getting a refund from $100 - $1,000 but there's no good way to predict any particular refund without figuring out the taxes.

Note: Yes, you can also make estimated payments where you send in money to the IRS (each quarter) over and above withholding, but I thought that would make the explanation too complicated, and few people do them, so I left them out of the above discussion.