The signature card has to say it
Under Banking Law § 675, a presumption of joint tenancy with right of survivorship arises only when the account's signature card actually shows that intent — language like "joint tenants" or "joint tenants with right of survivorship." New York courts have repeatedly held that the presumption simply doesn't apply when the account documents don't contain that necessary survivorship language, even if the account is functionally "joint" in the sense of having two names on it.
A missing card isn't automatically fatal
One New York Surrogate's Court case shows the presumption can still be established even without the original signature card, if there's clear enough proof the deposit was made and credited with survivorship intent. In that case, testimony from the bank employee who opened the account — establishing that the bank's policy was to open only survivorship accounts for two-name deposits, and that she'd told the account holders this — was enough to trigger the presumption despite the bank having lost the original card.
Rebutting the presumption
Once the presumption does apply, the burden shifts to whoever is challenging the survivor's claim. They can overcome it by establishing fraud, undue influence, or lack of capacity — or by tendering direct or substantial circumstantial proof that the account was opened as a convenience only, without any intention of giving the other party a genuine present beneficial interest in the funds.
The "convenience account" fight
This convenience-account theory shows up constantly in New York estate litigation. A parent who adds one adult child to a bank account purely so that child can help pay bills or write checks may not have intended to give that child real ownership of the money — but the signature card often doesn't distinguish "convenience" from "genuine joint ownership." If the added party can't show clear survivorship intent, or if the challenger successfully proves the account was convenience-only, the funds pass to the original owner's estate instead of automatically to the survivor — which can mean the money gets split among all the children under a will or intestacy, not kept entirely by whichever child happened to be on the account.
Why the account title matters more than intent alone
An advisor considering whether to add a child's name to an account for estate-planning purposes has to think carefully about which outcome they actually want. Naming one child "with rights of survivorship" gives that child the whole balance outright at death, regardless of whether the parent assumed the child would voluntarily split it with siblings afterward — there's no legal guarantee that happens, and the resulting sibling conflict is a frequent source of New York litigation.
Life insurance and retirement accounts
Life insurance and retirement accounts like a 401(k) or IRA follow the ordinary rule: the named beneficiary receives the asset directly, outside probate, as long as they're alive when the owner dies. Either one becomes part of the probate estate only if no beneficiary was ever named, every named beneficiary predeceased the owner with no contingent beneficiary in place, or the policy or plan names the owner's own estate.