Volt Credit 101, Federal
I'll be the first to admit that as usual nothing is easy when it comes to the fed's but let's clear this up. You don't get money if you haven't paid, mostly.
Ex. Let's assume for arguments sake that for your adjusted gross income, after deductions, personal credits, etc. that your tax LIABILITY for the year is $10,000. This is the figure you'll have to settle up with Uncle Sam at the end of the year. Now, let's also throw in that you bought a Volt and are eligible for a $7,500 tax CREDIT, not necessarily a refund, mostly again.
It's now the end of the year (2011), and time do do your tax return
Scenario #1: You owe $10,000 and you've paid in your $10,000. So normally you'd owe no more and get nothing back but since you bought the Volt your tax liability has been reduced by the $7,500 CREDIT which now brings your liability to $2,500 so you've overpaid by $7,500 and you'll get that as a refund.
Scenario #2: End of year and you've only paid in $5,000 of the amount you actually owe so you'd normally owe another $5,000. The Volt has again reduced your liability to $2,500 but you'll only get $2,500 back since you only paid in $5,000. Everyone's going to ask, "why don't I get back the $5,000", because you owe $2,500 in taxes.
Scenario #3: End of year and you've managed to not pay in anything so you'll be sending the gov a check for $2,500. Remember, you owe $10,000 - $7,500 = $2,500 owed in taxes and since you've not paid, you do now so you'll ONLY pay Uncle Sam $2,500 in taxes this year. But you will be sending him a check and NOT getting anything back.
Example #2, your tax liability for the year is anything less than the Volt's $7,500 credit, $5,000, $3,000, etc. The Volt credit effectively reduces your tax liability to $0 so you ONLY get back an amount equal to whatever your tax liability was LESS whatever you haven't already paid in.
I.e., your liability is $5,000 and you've paid in $5,000. You'll get the $5,000 back, but NO MORE.
Your liability is $5,000 but you've only paid in $2,500, you'll get $2,500 back and no more because the Volt credit reduced your tax liability to $0 and you have paid in $2,500, so you get it back.
The ONLY way you actually get a full refund of $7,500 is if; 1) your tax liability is $7,500 or more and; 2) you've paid by the end of the year, $7,500 or more in taxes.