It looks like married couples, with 3 kids qualify for over 8k a year in tax credits, if they earn less than 50k per year.  So, if that couple earned 30k, would they basically get everything they paid in taxes and social security back, plus several extra thousand dollars?  

Married filing jointly with three kids income limit to receive any earned income tax credit is $51,567.  The amount of credit is based on income though. In this example filing jointly with 3 kids  the credit would be higher if they earned $16,000 instead of $50,000. If they earned $5,000 instead of $16,000 it would be less too.

There is also the child tax credit is not refundable but lowers their liability. Some  families may also get the additional child tax credit which is refundable.

For couples without children they may qualify for earned income credit too but the maximum credit is much less (under $500)  and the income limits are lower.

I don't know how to figure federal income tax, so not sure about the specific $30,000. Their earned income credit would be over $4,000 though.

~Tiffany

So, it sounds like you can depend on getting everything withheld from your paychecks back, through the credits and maybe a little extra.  It sure seems hard to find clear and easy to understand tables on the earned income tax credit though.

This is why h&r block is full of young families with beaters the first week in Feb.

"beaters"?? Is it safe to assume that is a car given the example in the next sentence?

I'd have had ours filed in January, but am still waiting on forms to be released for e-file thanks to the government's last-minute decision-making. It's all supposed to be ready by Friday, so we'll see.

Here's an earned income tax credit calculator for 2012.