I did have a job without withholding, and yes come April 15th, you have to pony up the full amount owed. And you can do it without penalty.
But...the real trick is being responsible enough to save so you can provide that 'lump sum' cash payment to the IRS and your state. It seems like a great idea to bank it, and get the interest, but even in a savings account with average interest rates, you're not minting real money and its probably worth what you do 'make' in those few months just to have it withheld properly.
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