I want to fill out my FAFSA early january but wont have tax return?

I want to fill out my FAFSA early but i know i wont get my parents tax information before that. Should i just use my parents previous tax information? How do i update it later when i do get it? Do i have to go to the financial aid office to update it? or
could i update it online when i get my SAR?

Don't use your 06 tax return. Wait until you and your parents fill out their 07 tax return and file. Some choose to do it in Jan, but then they have to go back and correct it later. If you wait and do it Early or mid Feb you will be okay. All the info will be accurate, and you won't delay it even more and risk the chance of messing it up and delaying it more by having to go in and make a correction.
You appy and make corrections at the same site. www.fafsa.ed.gov

Wait until you get the tax info.or your parents could look at their last check stubs so that they know what they made for the year. Most employers have sent out the tax info before the end of January so you will still have plenty of time to do the FASFA

If you fill out your FAFSA online, you can go back any time you want and change or add information. Do not use your parents old tax return information. The least you can do is fill out as much as you can, and then save the application for later on when you get the rest of your information.