T Tax Co‑Pilot FORM 1120 Open the workbench
THE AI CO-PILOT FOR FORM 1120

Your
done with judgment.

Tax Co-Pilot reads the client's documents, computes the return deterministically, and flags what's wrong — showing its work on every line. A CPA approves everything that matters.

Enter the workbench → See a figure trace
✓Nothing files without a CPA
✓Every figure carries a reference
✓Computed, never scraped
0workpaper tabs in one engagement
0%of measured figures carry a reference
0regression checks on every change
0tax numbers typed by the model
§ 01ONE ENGAGEMENT, ONE TRUTH

Upload the documents once. Every schedule reads from the same cells.

Extraction turns the client's files into an evidence base — cells that keep their document, page and row. The portal and the bench both read from it, and everything recomputes when it changes.

READS FROM THE CELLS
Client portal
→A live estimate in plain English — no line numbers, no jargon
→What's missing is named — "December bank statement" becomes a request
→The return, explained before it's approved
EXTRACTED ONCE
The evidence base
Trial balance General ledger Fixed-asset register · 9 assets Bank statements · 12 mo Prior-year 1120 Payroll summary
Every cell keeps its document, page and row. Gaps are named, never silently defaulted.
READS FROM THE CELLS
Preparer bench
→Schedules prefill from cells — 4562, 1125-A and the M-1 assemble themselves
→Edit anything; ties re-check on every change
→Diagnostics gate the export — until they clear, nothing leaves
§ 02THE DETERMINISTIC ENGINE

The engine owns the math.

The model reads documents and proposes inputs. Every total on the return is computed by a deterministic engine — versioned, cited, and reproducible. Free-form model text never becomes a filed number.

✓The whole depreciation chain — §179 limits and phaseout, §168(k) bonus, MACRS conventions, §280F caps — never typed by hand
✓The hard parts too — DRD tiers, the §163(j) limitation with Form 8990, the §172 NOL
✓Temperature-0 extraction — stamped prompt and model version; the same documents give the same answer
✓Whole-dollar honesty — the filed return foots exactly, components to totals, the way the IRS expects
Trace a figure yourself →
Form 4562 · line 22 — click any figure to trace
LIVE DEMO · LOOPS
$1,482,971
Total tax depreciation — computed, not entered
01
§179 expensing$250,000 elected, within the aggregate limit
IRC §179
02
§168(k) bonuson the basis remaining after §179
IRC §168(k)
03
MACRS year 1half-year convention on the remainder
Pub 946
▦
Source: G-1 fixed-asset register9 assets extracted from the client's upload
document
MODEL PROPOSES·ENGINE COMPUTES·CPA DECIDES
§ 03THE PORTAL & THE BENCH

One return, two honest views.

Clients get a paper-warm portal that speaks plain English. Preparers get a steel workbench with schedules, diagnostics, and the edit ledger. Same numbers underneath — two rooms, two jobs, one truth.

✓Chat-first intake — upload, answer, and watch the estimate form in real time
✓Diagnostics that block filing — source conflicts and failing ties stop the gate, not a nag
✓Role-gated release — staff prepare, partners release, clients approve
✓The full package — 1120 with J, L, M-1, M-2, 4562, 1125-A/E and 8990 in one view
Open the workbench →
§ 04EVERY NUMBER, SOURCED

A figure you can't trace is a figure you can't defend.

Tax Co-Pilot measures reference coverage, re-verifies citations against the official text, and refuses to export what it can't source.

✓Coverage, measured — a meter counts every figure with a reference, and the ratchet only moves toward 100%
✓Clickable authority — every citation chip opens the controlling official text, not a tooltip
✓Re-verified, not remembered — citations are checked against the text they cite, never trusted from model memory
✓Proof ships with the file — a References sheet in every Excel export, an appendix in every PDF; unsourced figures block the gate
§ 05FOR THE FIRM

Built for the ten-minute return.

The hours of retyping, footing, and cross-checking collapse into minutes of review — with the record to show for it.

1120

A first draft the same day

Portal intake to a working return — ties checked as it builds.

M-1 ties ✓ 100% referenced ✓
Start one →

Every figure carries its source

Missing references are named and block the export — never silently defaulted.

MISSING DOCUMENT

December bank statement

Needed for the B-2 cash tie · requested in the portal
blocks the export gate · task created

Approval is a record, not a vibe

#A-2026-114 · Ruth O. · Aug 15, 2026 — a name and a timestamp on every sign-off.

An engagement, end to end

SAMPLE ENGAGEMENT · WK 33
§ 06THE EDIT LEDGER

Every change carries its reasons.

Nothing here edits silently. Each write — human or AI — lands in a ledger with the old value, the new value, the author, the why, and the rule it relied on.

Change
Author
Basis
Rule / authority
Status
Meals $21,000 → $18,400B-1 · source conflict resolved
Co-pilot, confirmed by Ruth O.
GL is higher authority
§274(n) · M-1 tie rule
accepted
§179 election · $250,000Form 4562 · within the aggregate limit
Tomás R.
G-1 asset register
IRC §179(b) · engine
accepted
COGS $812,440 → $818,2901125-A · inventory true-up
Co-pilot
Client's stated subtotal
§471 · footing rule
awaiting Ruth

Co-pilot · proposing a §163(j) limitation — Form 8990 attached, waiting for a reviewer

Rendered from the live prototype's ledger schema — old → new, author, basis, rule, disposition.
§ 07ROLES & ACCESS

Everyone sees exactly their slice.

DKDanaclient
TRTomásstaff
RORuthpartner
Capability
Client
Staff
Partner
See the engagement & live estimate
✓
✓
✓
Upload documents & approve the return
✓
—
—
Prepare schedules & propose edits
—
✓
✓
Accept / reject ledger changes
—
—
✓
Release filings & exports
—
—
✓
Manage team, roles & invites
—
—
✓
Clients never see the bench

The portal speaks plain English and shows the estimate. Schedules, diagnostics and the ledger stay in the workbench.

Every action lands in the log

Edits, accepts, rejects, notes and releases are recorded with the signed-in identity and a timestamp.

Sign-off carries identity

prepared  · tomas@firm.cpa
released  · ruth@firm.cpa
approved · dana@client.com

§ 08GUARDRAILS

Built to be checked.

Audit trail on everything

Who, what, why, and under which rule version. Exports are logged, and approvals carry names and timestamps.

Computed, never scraped

Totals are deterministic sums of extracted cells — the model proposes inputs, never final numbers. A 1,305-check regression gate guards every change.

Diagnostics block, not nag

A failing M-1 tie or an unresolved source conflict stops the export gate. Dismissals are recorded and reversible.

Honest about its limits

Preparation software, not tax advice — and a proof of concept, not an e-file provider. Judgment belongs to the CPA, and nothing files without one.

§ 09PLAIN ANSWERS

Is this tax advice?

No. Tax Co-Pilot prepares workpapers and spots issues against versioned rules. Judgment calls belong to you and your client — which is why nothing files without a CPA.

What does the AI actually write?

It reads documents and proposes inputs at temperature 0. Every total is computed by the deterministic engine, and free-form model text never becomes a filed number.

Who can see our data?

Access is role-scoped: clients see their engagement, staff prepare, partners release. Intake is encrypted at rest, and nothing you store is used to train models.

Why do the portal and the bench look different?

Two rooms on purpose: a paper-warm portal for clients and a steel workbench for preparers. Same figures, same ledger — different jobs, different light.

What's real today?

Form 1120 with Schedules J, L, M-1, M-2 and Forms 4562, 1125-A, 1125-E, 8990; Excel, PDF, Drake and CCH exports with a References sheet; the portal, the bench, and the activity log. It's a proof of concept — not an IRS-authorized e-file provider.

Where do I start?

Enter the workbench and open an engagement. Upload a trial balance and a fixed-asset register, watch the return assemble — then click any figure and follow it home.

See a return build itself in ten minutes.

Bring a client's documents. Watch the workpaper assemble — figures, references, diagnostics and all — then take command of every number.

Enter the workbench → Client portal