Checks the taxpayer's completed draft packet for a federal return and, when it passes, holds it as an unsigned draft and returns the link to the filing page; otherwise returns a list of problems to correct. This call files nothing and sends nothing to the IRS: the taxpayer reviews, signs and files personally on the filing page. Takes the filing session's continuationHandle, completedReturnPacketJson (the whole packet as one JSON string, in this server's packet schema) and packetSchemaSha256 (that schema's digest); any other argument, including a schema argument, is refused by name. The packet holds only facts the taxpayer stated in this chat and figures printed on documents the taxpayer gave in it. The tax year is return.taxYear=2025 inside the packet. Returns status filing_session_ready with one filingSessionUrl when the packet is accepted: the only response that contains the link, which the taxpayer opens to give permission, review the return and sign it. Otherwise returns blockers, each with a path, a rule and a plain detail, and no link: that packet is not kept, every blocker that can be checked arrives in one response, a check that depends on a missing or refused answer runs once that answer is corrected, and the same handle accepts a corrected packet. No filing link is issued until the packet holds every item the return and the filing page need from this conversation, the agentIdentity section included; each missing item comes back as its own blocker naming its path and the exact question for the taxpayer, all in one response, and only what the law has the taxpayer enter personally, the review and the signature are left for the filing page. A link left unopened for 15 minutes lapses, and sending the same packet again returns a new one. An accepted packet is held until the taxpayer gives permission on the filing page; declining there, or expiry, erases it. Federal only: no state, territory or local return is filed. The return has no taxpayer identity fields: the taxpayer's own details go only in the packet's separate, required agentIdentity section, which the filing page shows for the taxpayer to confirm. Business identifiers printed on each source form, such as an employer's or payer's name and EIN, are packet fields. The filing session's status reports progress.