Quick answer: the single most common mistake is signing the trust but never deeding real estate into it. An unfunded trust leaves the estate in full Illinois probate. See what that would cost in the Illinois probate vs living trust calculator.
1. Real estate never deeded into the trust
Illinois real estate requires a new deed transferring the property from the individual owner's name into the trust's name, and that deed must be properly recorded with the county recorder. A trust document alone, however carefully drafted, does not move title on its own — this is exactly the step complete Illinois trust packages typically include as a deliverable, precisely because it's so easy to skip.
2. Financial accounts left titled individually
Bank and brokerage accounts need to be either retitled into the trust's name or given trust beneficiary designations. Accounts left in an individual's name pass outside the trust and typically land back in the probate estate.
3. Assets acquired after the trust was created
A trust only covers what's actually transferred into it. A new account, vehicle, or newly purchased property acquired after the trust was signed needs its own separate transfer — the trust doesn't automatically absorb future acquisitions.
4. Assuming the small estate affidavit is a safety net
A local probate attorney can review your estate — many offer a free consultation.