Regardless of Intuit's published data retention policies, there's really no way for regular retail customers to confirm what detail of info they're retaining, where they are retaining it, and for what length of time they're retaining it.
Also, even if Intuit customer support claims they have no access to previously transmitted returns, we should assume that their their legal department has unlimited access to any returns that their system administrators are able to locate (see the fine print quoted above).
In any case we can rightfully assume that online tax preparation exposes our tax return information to a much greater attack surface, i.e. an Internet-facing publicly accessible web site storing tax return information for at least as long as it takes a customer to prepare and transmit it. But using a desktop product to transmit a completed return is likely something more akin to a temporary SSH session that only lasts as long as necessary to transmit to Intuit's forwarding servers. (And hopefully Intuit's server architecture has their online preparation web server and storage completely separated from a set of store & forward servers that transmit completed returns to the relevant tax authorities -- but we can't be sure of that either...)
So the IT security guy in me (and yeah I've been involved with establishing legal holds on data with evidentiary significance) says that the risks associated with online tax preparation should be avoided if at all possible. TRUST NO ONE. 👁
