MSFT Partial ACATS Transfer: Cost Basis Lineage Defense
PROOF LOG #013
MSFT Partial ACATS Transfer: Cost Basis Lineage Defense
When part of a position moves, cost basis and source-lot lineage still need to remain reviewable.
A partial transfer can make the Schwab-side piece look like a fresh lot.
FDL reattaches the Schwab sale to the original Fidelity lot and keeps the remaining 1,200 sh intact.
A partial ACATS transfer moved 800 sh of MSFT from Fidelity to Schwab in January 2025.
The transfer moved part of the position. It did not create a new tax history.
The review issue is whether cost basis, tax lots, and source-lot lineage remain connected after the partial transfer.
FDL prepares the later Schwab sale against the original October 2023 source lot, preserves $264,000 of cost basis, and keeps the remaining 1,200 sh open on the same lineage.
This is not tax alpha.
This is partial-transfer lineage defense.
Proof Summary
Problem: A partial ACATS transfer can make the transferred MSFT shares look disconnected from the original tax lot.
Prepared input: Using the operator’s explicit lot match, FDL runs the prepared state, reconnects the Schwab sale to the original Fidelity source lot, and preserves the remaining MSFT position.
Board result: Tax Report shows 800 sh sold with $264,000 basis and $72,000 LONG gain, while Audit Trail preserves 1,200 sh still open on the same lineage.
Boundary: FDL does not create tax alpha here. It verifies prepared, in-scope partial-transfer lineage and basis continuity through deterministic outputs.
WATCH THE RECONSTRUCTION
Watch the prepared transfer artifact be resolved, the Schwab sale be reattached to the source lot, and the remaining MSFT position remain intact.
- Original lot: 2,000 sh MSFT bought in October 2023 at $330
- Partial ACATS in January 2025 moved 800 sh to Schwab
- transfer rows can read like a new lot if left unreconciled
- FDL matches the March 2025 Schwab sale back to the original source lot
- Tax Alpha Dashboard stays neutral; this is continuity defense, not tax-arb
- Tax Report shows 800 sh sold, $336,000.00 proceeds, $264,000.00 basis, $72,000.00 LONG gain
- Audit Trail preserves 800 sh consumed and 1,200 sh still open on the same lineage
EXECUTIVE PROOF
Broker Blind Spot
- partial transfer can look like a new purchase
- acquisition date can appear reset to the receiving-side row
- basis can detach from the original source lot
- the transferred piece and the remaining piece can both become ambiguous
FDL Registry of Truth™
- Tax Alpha Dashboard stays neutral because no alpha bucket is being manufactured
- Tax Report shows the prepared filing result
- Audit Trail preserves the source lot, partial consumption, and remaining open balance
- the same original lot governs both the sold 800 sh and the remaining 1,200 sh
PHASE 1 — THE ARTIFACT
An 800-share MSFT position moved from Fidelity to Schwab through ACATS in January 2025.
At the transfer layer, that receiving-side row can look like a new lot.
That is the artifact.
What moved was the asset.
What must not move is the source truth.
PHASE 2 — THE CONTROLLED RECONNECTION
FDL does not guess what the transfer row means.
The operator neutralizes the transfer artifact and explicitly matches the Schwab sale back to the October 2023 source lot.
Run Audit pushes that prepared state through the record.
This is not automatic transfer repair.
It is a controlled, reviewable reconnection.
PHASE 3 — THE PARTIAL LOT REMAINS INTACT
The March 2025 Schwab sale consumed 800 shares of the original 2,000-share lot.
That left 1,200 shares still open on the same lineage.
The source lot was not replaced. It was partially consumed.
Partial transfer is where continuity must split correctly without breaking.
FORENSIC EVIDENCE
What must remain intact
- Original acquisition monthThe sale must still inherit October 2023.
- Basis continuityThe sold 800 sh must carry $264,000.00 of original basis.
- Split-lot identityThe original lot must show 800 sh consumed and 1,200 sh remaining.
What FDL makes legible
- Tax Alpha DashboardShows no alpha event; this is continuity defense, not a tax-arb story.
- Tax ReportShows the visible filing result: $72,000.00 LONG gain.
- Audit TrailRecords the source lot consumed and the remainder still open.
This is the point of the white-box architecture:
the correction is visible, not implied.
WHY THIS CASE MATTERS
ACATS is operationally common.
Partial transfer is where record quality quietly breaks.
For UHNW households using multiple custodians, the real risk is not the movement.
It is the silent conversion of source-lot history into a fake new-lot narrative.
This is where reviewable transfer-lineage infrastructure matters.
WHAT FDL IS SHOWING HERE
FDL is not creating a new answer.
It is enforcing the prepared one.
The source lot remains the October 2023 MSFT lot. The Schwab sale is matched back to that source lot. Tax Report reflects the correct realized result. Audit Trail shows why 1,200 shares still remain open on that same lineage.
The value is explicit, deterministic, reviewable, and lot-level traceable.
CHOOSE YOUR NEXT STEP
FDL — deterministic tax infrastructure for prepared, in-scope records.