I want to know if the IRS can take my lump sum? I got approved for SSI and will be receiving SSDI after my 5 months end. I waiting on my lump sum now, and just wanted to know will they touch it are not. I only owe 2,000. I hear a lot of people who say they will, and then say they won't.

The IRS can take what they are owed - the retroactive is considered a windfall.
Not only that, but if you got SSI for 5 months, SSDI (federal) goes to pay back SSI, a state program of welfare.
I'm not sure who gets first crack at it.
There are exceptions if you will be homeless directly as a result, such as a landlord who has been waiting for rent.
Unless the law has changed and I haven't heard.

I know they will take it if you were receiving it as some sort of supplement to keep you going while waiting. If Its an old debt then they might not catch it right away and garnish later monthly money.

Unless you can show the IRS that confiscating the lump sum to settle an old tax debt will dramatically affect you, they WILL take it.