Quick answer: the most common mistake is never recording a new deed into the trust's name for real estate. The most common DC-specific mistake is assuming a basic joint trust automatically preserves both spouses' non-portable exemptions when it doesn't. See how the numbers change in the DC probate vs living trust calculator.
Signing ≠ funding
1. Real estate deed never recorded — the #1 mechanical mistake
Moving real estate into a trust requires a new deed, signed and recorded, naming the trust as owner. This is the step most often skipped. Left undone, that property remains a probate asset — subject to the full Probate Division process, including the periodic accountings, regardless of the trust document sitting in a drawer.
2. Assuming a joint trust automatically preserves both exemptions — DC's own risk
Because DC's estate tax exemption isn't portable between spouses, simply signing a basic joint revocable trust doesn't automatically preserve both spouses' $4,988,400 exemptions. A specific credit shelter or similar structure has to be built for that purpose — without it, leaving everything to the surviving spouse can waste the first spouse's exemption entirely, the same risk that exists without any trust at all.
3. Financial accounts left titled individually
Bank and brokerage accounts don't join a trust automatically. Each one has to be retitled into the trust's name, or the institution needs a copy of the trust document plus a change-of-ownership form. Accounts opened after the trust was created are especially easy to forget.
4. Treating the small estate proceeding as a safety net
DC's small estate proceeding — $80,000 or less — is a genuine shortcut for modest, unfunded assets. It's not a backstop for a house or a sizeable account left outside the trust by mistake; those amounts require full probate, including the periodic accounting cycle.
A local probate attorney can review your estate — many offer a free consultation.