I have been collecting a ssi disability check for about a year now and I owe about 70,000 dollars in back taxes.Can those back taxes be taken out of my check or can I loose my check and my medicaid.

If the SSI check is your only source of income and you can show that losing ANY PART of the SSI check will have a significant adverse effect on your financial situation, then that check is immune from any IRS or state garnishment action.

However, you need to be proactive in this matter. Contact the IRS Taxpayer Advocate to find out what forms need to be filed to prevent a garnishment action by the IRS.