Professional resource
CPA / Tax Professional Client Document Checklist for Incomplete Cost Basis
Published 2026-09-02 · Reviewed 2026-09-02
A plain-language handoff checklist for CPAs and tax professionals helping a client assemble incomplete historical investment records.
What to ask the client to gather
- Current and historical statements from every known brokerage or transfer agent
- Trade confirmations, purchase notices, and reinvestment records
- 1099-B and other relevant tax forms already received
- Transfer, ACATS, DRS, registration, and account-closing documents
- Corporate-action notices, including mergers, splits, and ticker changes
- Prior tax workpapers or schedules that identify how a figure was sourced
- Estate, inheritance, or gift records when the position was not purchased directly
- A written list of known firms, approximate dates, account identifiers, and missing periods
Ask for a gap map, not just a file dump
For each unresolved position, ask the client to identify the security, approximate acquisition date, quantity, known account or firm, and the specific question that remains. A short gap map helps distinguish missing documents from conflicting documents and unsupported assumptions.
Ask the client to preserve originals and label copies clearly. Redacted copies may be appropriate for handoff, but retain enough context to identify the issuer, period, and relationship to the position being reviewed.
Suggested review-status labels
| Label | Meaning | Next Action |
|---|---|---|
| Confirmed by source document | The cited record directly supports the detail. | Retain the source reference and mark the detail confirmed. |
| Candidate detail requiring review | The detail is plausible but needs professional review. | Keep it separate from confirmed facts until reviewed. |
| Supported indirectly by related records | Related records support context but not the full detail. | Identify the missing direct source or leave the gap open. |
| Conflicting records — professional judgment required | Available records disagree or cannot be reconciled here. | Preserve both records and escalate the conflict for review. |
| Missing source — request still open | The needed record has not been located or received. | Record the request, recipient, date, and follow-up needed. |
| Out of scope for this review | The question is outside the defined review scope. | Document the boundary and identify the appropriate next owner. |
Where Investment Vault may fit
Investment Vault can help a client organize supported PDFs, review candidate events, keep confirmed entries linked to source documents, and prepare a clearer handoff. It does not determine tax treatment, replace professional judgment, or guarantee that a reconstructed figure is complete or accepted.
Sources for further reading
A clearer client handoff
Investment Vault may help a client organize source PDFs and confirmed events before sharing a package with a professional.