As a practical matter, it is generally best to look at your client’s financial status at 3 months, 6 months, and one year.
The Internal Revenue Manual Part 5. Collecting Process Chapter 8. Offer in Compromise Section 5. Financial Analysis Subsection 3. 184.108.40.206 (09-30-2013), which Refers to Taxpayer Submitted Documents, states “Collection Information Statements (CIS) and related documentation submitted with an OIC should reflect current information as of the date of the OIC submission.”
If during the investigation, the financial information becomes older than 12 months and it appears significant changes have occurred, a request for updated information may be appropriate. Prior to contacting the taxpayer, attempt to secure the necessary verification through internal sources. If taxpayer contact is required, contact via telephone is preferred to expedite case processing.
In certain situations, information may become outdated due to significant processing delays caused by the Service and through no fault of the taxpayer. In those cases, it may be appropriate to rely on the outdated information if there is no indication the taxpayer’s overall situation has significantly changed. Judgment should be exercised to determine whether, and to what extent, updated information is necessary. If there is any reason to believe the taxpayer’s situation may have significantly changed (i.e. change of employment, loss of job, etc.), and substantiation cannot be secured via internal research, secure a new CIS.
I hope this helps.
If you need additional help, please feel free to contact me directly.