Box 4 is withholding. The IRA custodian might have withheld some for taxes automatically. Do you remember that there was withholding and you did not get the full amount?
In any case, the distribution is subject to regular income tax, but not the penalty. Your amended tax return will calculate the amount of tax you owe, and the withholding will be applied against that tax. If you owe more, you will be told to pay it, and if the withholding is more than the tax owed, you would get a refund.
So yes, the $571 is taxable income, the tax on that is likely to be between $68 and $137, depending on your filing status and other income (12-24%), the $57 of withholding goes to your credit, and you will likely have to include a check for the rest with your amended return. This will all happen automatically.
