A return starts with an intake file: the folder holding identity documents seen, information statements gathered, the prior-year return, and IRS notices, each marked verified or still open. The preparer works from the checklist, so a file with two unchecked boxes stays unprepared while those boxes are chased. A signed checklist might show photo ID seen, prior return requested, and one notice still to collect. Preparation begins when every box is marked.
This checklist is good office practice rather than an IRS rule. The rule underneath it is in Circular 230: a preparer may generally rely in good faith on what the client provides, without checking every figure, but may not ignore what that information implies and must ask reasonable questions when it looks incorrect, inconsistent or incomplete. An open line on the checklist is where those questions get asked.
Worked example
Preparer Elise meets Mara, who shows a driver's license and a stack of wage statements but left the prior-year return and an IRS letter at home. Elise logs four lines: photo ID seen, wage statements gathered, prior return open, IRS notice open. She pauses preparation and gives Mara a request list for the two open items. The file waits as unverified rather than half-prepared.