Module S5 — The OBBBA rename trap

AI trained before July 2025 defaults to pre-OBBBA terminology (FDII, GILTI, §174, $10K SALT). The prompt-level framing, post-response audit, and printable rename map that catch stale tax law in AI output before it reaches a return.

AI Tax Practitioner Editorial

Published May 27, 2026 ·16 min read ·Last reviewed May 27, 2026

The 30-second version. Frontier AI models trained before July 4, 2025 know nothing about OBBBA. Models trained through mid-2025 know it partially. Models with web search on retrieve a corpus where pre-rename content (FDII, GILTI, §174, $10K SALT cap, uniform 100% §1202) still dominates. The result: AI output on TY2025+ tax questions defaults to pre-OBBBA terminology unless you frame the prompt against it. This module gives you the prompt-level framing, the post-response audit, the rename reference card, and the per-vendor calibration to catch this Monday morning. The discipline takes 5-10 minutes per research session; the failure mode it prevents is the Mata v. Avianca / Thomas v. Commissioner pattern applied to stale tax law.

Why this module exists

OBBBA (One Big Beautiful Bill Act, Pub. L. 119-21, signed July 4, 2025) made eight load-bearing changes to terminology and substance that an AI doing tax research has to know about:

Old name	New name	IRC section	Effective	Substantive change
FDII	FDDEI	§250(a)(1)(A)	TY2026+	37.5% → 33.34% deduction; QBAI struck; new IP/depreciable-property exclusion
GILTI	NCTI	§951A / §250(a)(1)(B)	TY2026+	50% → 40% deduction; QBAI struck; §960(d) FTC haircut 20% → 10%
§174 R&D capitalization	§174A R&D expensing	§174A	TY2025+ retro	Immediate expensing restored
SALT cap $10K	SALT cap $40K	§164(b)(6)	TY2026+	4× increase; high-income phaseout
§1202 100% uniform	§1202 tiered 50/75/100	§1202	Stock post-7/4/2025	Tiered at 3/4/5 yr; per-issuer cap → $15M; aggregate threshold → $75M
§163(j) ATI definition	§163(j) ATI restored to EBITDA	§163(j)	TY2025+	Depreciation + amortization no longer reduce ATI
§168(k) bonus sunset	§168(k) 100% permanent	§168(k)	Post-1/19/2025	Sunset removed
1099-K $600 threshold	1099-K $20K / 200 txn	§6050W	TY2025+	Reversion to pre-ARPA threshold

A practitioner doing AI-assisted research on any of these in 2026 gets one of four failure modes: pre-OBBBA training cutoff (AI doesn’t know OBBBA exists); mid-2025 cutoff (mixed terminology); retrieval-corpus dominance (web search surfaces pre-rename law-firm posts); or regulation-vs-statute asymmetry (Cornell LII §250 says FDDEI but Treasury Regs §1.250 still say FDII). The articles tell you why all four fail. This module gives you the operational catch.

The Monday-morning sequence (5-10 minutes per research session)

Step 1 — Frame the prompt against the trap (30 seconds)

Don’t open with the substantive question. Open with framing. Use Artifact 1 — Pre-question framing prompt below. It loads the OBBBA cutover date, the required post-rename terminology, and the citation requirement into the AI’s context. This single prompt catches 70-80% of the failure modes.

Step 2 — Ask your substantive question (variable)

Whatever you needed the AI for. The framing prompt does its work upstream — you ask the question normally.

Step 3 — Run the output-audit prompt against the response (2-3 minutes)

After the AI answers, feed the answer back with the audit prompt. Use Artifact 2 — Output-audit prompt below. Expected output: a numbered list of any stale terminology, stale rates, stale effective dates, or omitted post-OBBBA references. Often the AI catches its own pre-rename slips when prompted — the model has the post-OBBBA knowledge but defaulted to the pre-rename version because the training-corpus center-of-mass sits there. If the audit returns zero flags AND the response had a non-trivial chance of stale terminology, run Artifact 3 — “What year is this?” verification prompt.

Step 4 — Verify primary-authority cites with a date check (2-3 minutes)

The audit prompt catches stale terminology. The date-check prompt catches stale citations. Use Artifact 4 — Source-date verification prompt below. Flag any source predating July 4, 2025 unless it’s a pre-OBBBA statute that wasn’t amended (§6694 preparer-penalty rules are unchanged — those pre-OBBBA cites are fine). If the AI’s sources are predominantly pre-July-2025 and the question is about TY2025+ law, the response is structurally suspect — re-prompt or run the question through Blue J / Checkpoint / Bloomberg Tax for the primary-authority pass.

Step 5 — Log the use (1 minute, per Module S1)

If the research touched client tax-return information, log per Module S1’s audit-trail template, with a note: “OBBBA-affected provision; rename-trap audit run, [X flags surfaced, Y resolved].” If the research was abstract (no client TRI), no log entry needed.

Artifact 1 — Pre-question framing prompt

Send FIRST in any AI research session touching an OBBBA-affected provision.

Before I ask my substantive question, set context: the One Big Beautiful Bill
Act (OBBBA, Pub. L. 119-21) was signed July 4, 2025 and made the following
load-bearing changes that you must reflect in your response:

1. FDII renamed FDDEI in Section 250(a)(1)(A); deduction 37.5% to 33.34%;
   effective TY beginning after Dec 31, 2025. QBAI offset struck. New IP /
   depreciable-property exclusion at 250(b)(3)(A)(i)(VII) for transactions
   after June 16, 2025.
2. GILTI renamed NCTI in Section 951A; 250(a)(1)(B) deduction 50% to 40%;
   effective TY2026. QBAI/DTIR struck. 960(d)(1) FTC haircut 20% to 10%. New
   960(d)(4) disallowance for 951A PTEP distributions after June 28, 2025.
3. Section 174 R&D capitalization replaced by 174A immediate expensing;
   effective TY2025+ with retroactive-election provisions.
4. Section 164(b)(6) SALT cap increased $10,000 to $40,000 effective TY2026
   (with high-income phaseout).
5. Section 1202 QSBS exclusion moved from uniform 100% to tiered 50/75/100% at
   3/4/5 year holding periods for stock issued after July 4, 2025; per-issuer
   cap raised to $15M; aggregate-asset threshold raised to $75M.
6. Section 163(j) ATI definition restored to EBITDA basis (depreciation and
   amortization no longer reduce ATI) effective TY2025+.
7. Section 168(k) 100% bonus depreciation made permanent for property placed
   in service after Jan 19, 2025.
8. The 1099-K $600 reporting threshold reverted to the pre-ARPA $20,000 / 200
   transactions threshold effective TY2025+.

Requirements for your response:
- Use post-OBBBA terminology (FDDEI not FDII, NCTI not GILTI, 174A not 174,
  $40K SALT cap, 1202 tiered) wherever the provision is OBBBA-affected.
- Cite both the IRC section AND the relevant OBBBA section where applicable
  (e.g., "Section 250(a)(1)(A) as amended by OBBBA Section 70321").
- For any rule still in transition (e.g., Treas. Reg. 1.250 not re-issued; IRS
  Form 8993 Dec 2025 revision still uses FDII), explicitly flag the
  regulation-vs-statute asymmetry.
- If your training data predates July 4, 2025, or you are uncertain about a
  specific OBBBA provision, say so directly rather than defaulting to
  pre-OBBBA terminology.

My substantive question follows in the next message.

The prompt is intentionally long — the AI’s behavior on the substantive question that follows is meaningfully better with the full framing. Bind it to a text-expansion snippet (::obbbaframe). Update it when the transition timeline changes (Treasury re-issues §1.250, Form 8993 TY2026 ships, etc.).

Artifact 2 — Output-audit prompt

After the AI gives a substantive response, send this as a follow-up in the same thread.

Scan your prior response for any of the following stale-OBBBA signals and list
each occurrence:
1. "FDII" where the current provision is FDDEI
2. "GILTI" where the current provision is NCTI
3. "Section 174" R&D capitalization where 174A R&D expensing now applies
4. "$10,000 SALT cap" where the current TY2026+ cap is $40,000
5. "100% uniform Section 1202 exclusion" without the tiered 50/75/100% framework
6. Section 163(j) ATI as a non-EBITDA computation
7. The 1099-K $600 threshold as current law
8. Section 168(k) bonus depreciation sunset that doesn't reflect OBBBA permanence
9. Any deduction percentage of 37.5% (FDII), 50% (GILTI), or 21.875% (scheduled
   FDII step-down) cited as current law
10. Any effective-rate calculation using pre-OBBBA percentages

For each occurrence, quote the sentence, identify which trap it falls into
(1-10), and state what the post-OBBBA-correct version should say. Output as a
numbered list. If you find zero occurrences, say "No stale-OBBBA signals
detected" and stop.

The AI is competent at this self-audit when prompted directly — false-positive ~5-10%, false-negative ~15-25% on subtle cases (especially when the body is correct but the summary slips). Artifact 3 is the second-line catch.

Artifact 3 — “What year is this?” verification prompt

If the output-audit returns zero flags and the question was non-trivially in OBBBA territory, run this.

Confirm your prior response would apply correctly to a TY2026 return filed in
2027 by:
1. Stating whether each statutory citation is post-OBBBA correct (with the OBBBA section where applicable)
2. Stating whether each percentage, threshold, or effective rate is post-OBBBA correct
3. Stating whether each form reference (Form 8993, Schedule B, K-1) is the current revision OR in transition
4. Identifying any place where your response would differ for TY2024, TY2025, or TY2026
5. If your response applies only to one tax year, state which one and what the answer would be for the other
For each item, quote the relevant sentence and state the verification result.

Asking the AI to confirm tax-year specificity forces it to surface where the question was ambiguous on year and where the answer differs by year. Its own internal consistency check often catches stale references the output-audit missed.

Artifact 4 — Source-date verification prompt

List every primary source you used or referenced in your prior response. For each:
1. Source title (IRC 250, Treas. Reg. 1.250(b)-1, IRS Form 8993, Notice 2025-78, a case, a ruling)
2. Publication or revision date
3. Whether the source content was updated after July 4, 2025 (Y/N/UNCERTAIN)
Flag each with: [POST-OBBBA — verified current], [PRE-OBBBA — verify still
applicable], or [UNCERTAIN — practitioner should verify dated source]. If you
used sources you cannot date with confidence, list them under [UNCERTAIN] and
recommend the practitioner verify the publication date directly.

Calibration: AI tools without web search are weak at this — they guess publication dates from training-corpus memory. Use it primarily with web-search-enabled tools (Claude with web search, ChatGPT browsing, Perplexity) or curated-research tools (Blue J, Checkpoint, Bloomberg Tax) that have explicit publication-date metadata. Without web search, the prompt is a stress-test of the AI’s self-awareness, not a verification.

Artifact 5 — The OBBBA rename map

Print and tape next to the monitor. The fastest catch happens when the rename map is in peripheral vision.

                    OBBBA RENAME MAP (effective TY2025-TY2026)

Old terminology               New terminology              Effective date
---------------------------------------------------------------------------
FDII                          FDDEI                        TY2026
Section 250(a)(1)(A) 37.5%    Section 250(a)(1)(A) 33.34%  TY2026
GILTI                         NCTI                         TY2026
Section 250(a)(1)(B) 50%      Section 250(a)(1)(B) 40%     TY2026
Section 960(d) FTC haircut 20%  Section 960(d) haircut 10%  TY2026
Section 174 R&D capitalization  Section 174A R&D expensing  TY2025 retro
SALT cap $10,000              SALT cap $40,000             TY2026
Section 1202 100% uniform     Section 1202 tiered 50/75/100  Issued post-7/4/25
Section 1202 per-issuer $10M  Section 1202 per-issuer $15M  Issued post-7/4/25
Section 1202 aggregate $50M   Section 1202 aggregate $75M  Issued post-7/4/25
Section 163(j) ATI excl. D&A  Section 163(j) ATI EBITDA    TY2025
Section 168(k) bonus sunset   Section 168(k) 100% permanent  Placed post-1/19/25
1099-K $600 threshold         1099-K $20K / 200 txn        TY2025+

NEW EXCLUSIONS (no pre-OBBBA equivalent)
---------------------------------------------------------------------------
Section 250(b)(3)(A)(i)(VII)  IP / depreciable property sales   Post-6/16/2025
Section 960(d)(4)             10% disallowance on 951A PTEP     Post-6/28/2025

TRANSITION TIMELINE
---------------------------------------------------------------------------
TY2024 returns    Use pre-OBBBA terminology and rates
TY2025 returns    Use FDII / GILTI / 174A (partial); apply 250(b)(3)(VII)
                  carve-out for transactions post-June 16, 2025
TY2026 returns    Use FDDEI / NCTI / new rates throughout

FORM REVISION STATUS (as of May 2026)
---------------------------------------------------------------------------
Form 8993         Dec 2025 revision still says FDII
Treas. Reg. 1.250 Pre-OBBBA, not yet re-issued
IRS Notice 2025-78  Dec 4, 2025 — proposed regs forthcoming on (VII)

AI TOOL STATUS (re-check quarterly)
---------------------------------------------------------------------------
GPT-5 base          Knowledge cutoff Sept 30 2024 (pre-OBBBA — frame prompt)
Claude Sonnet 4.5   Reliable through Jan 2025 — partial OBBBA awareness
Claude Opus 4.5     Reliable through Aug 2025 — better OBBBA awareness
Blue J              Curated post-OBBBA corpus — most reliable on FDDEI/NCTI
Checkpoint / CoCounsel  Updated through Q1 2026 — reliable
Bloomberg Tax       Updated continuously — reliable
CCH AnswerConnect   Updated through Q1 2026 — reliable

(Always verify in primary authority before signing — never trust the AI as the
final word on Section 10.34 substantial-authority claims, per Module S3.)

Update cadence: quarterly. The form-revision status, AI tool cutoffs, and Treasury regulation status will shift.

Artifact 6 — Client-facing OBBBA explanation (60-second script)

Three drop-in variants for the three client segments that actually ask “did the tax law change?”

For the C-corp shareholder / executive client (FDDEI / NCTI):

Yes, several provisions in your business return are changing. The OBBBA bill signed July 4 last year renamed and adjusted two deductions you may have seen on your filings — the FDII deduction is now called FDDEI, and the GILTI inclusion is now called NCTI. The rates changed: FDDEI moves from 37.5% to about 33% on the deduction side, NCTI from 50% to 40%. The effect on your effective rate depends on whether you have foreign sales, foreign subsidiaries, or both. For TY2025 we’re using the old labels because the IRS forms haven’t been re-issued yet. For TY2026 — filed in 2027 — everything carries the new labels. No action needed from you right now.

For the small-business / Schedule C / §199A QBI client (§174A, §163(j)):

Yes, two changes are relevant for you. Section 174A restored immediate expensing for research-and-development costs starting in TY2025 — if your business has R&D activity that was being capitalized, we may have a one-time election to consider. Section 163(j) changed how business-interest deduction limits are calculated; depreciation and amortization no longer reduce the income base, which means more interest is generally deductible. The effect depends on your specific interest expense and depreciation. I’ll surface specific numbers when we work through your return.

For the HNW individual / SALT / QSBS client:

Yes, three provisions moved. The state-and-local-tax deduction cap moves from $10,000 to $40,000 starting in TY2026 — meaningful if you’ve been hitting the cap. The §1202 Qualified Small Business Stock exclusion changed: stock you acquire after July 4, 2025 falls into a tiered structure (50% at 3 years, 75% at 4, 100% at 5), with the per-issuer cap rising from $10M to $15M. For stock you owned before July 4 2025, the original rules apply. If you’re considering new QSBS-eligible investments, the timing now matters more than it did under the uniform 100% exclusion.

Each is ~120 words, cites the OBBBA date but not the section numbers (those are practitioner-side), and closes with “I’ll handle this on your return” rather than “you need to do something.”

FAQ

Can I skip Artifacts 2-4 if the question doesn’t touch the eight affected provisions?

Yes. Run the framing prompt (Artifact 1) only if the question touches any of the eight; skip the audit/verification if the AI’s response doesn’t engage OBBBA-affected provisions. Edge case: if the AI introduces an OBBBA-affected provision you didn’t ask about, run the audit anyway.

Are §6694, §6695, §7216, Circular 230 OBBBA-affected?

No. Those are unchanged by OBBBA. AI references to them can use pre-OBBBA primary authority without triggering the rename trap. The §10.22 due-diligence reflex still applies to OBBBA-affected substantive positions — see Module S3.

Which AI tool is most reliable on OBBBA in May 2026?

Blue J has the most reliable post-OBBBA corpus among tax-specific tools; Checkpoint Edge and Bloomberg Tax are also reliable. Among general-purpose tools, Claude Opus 4.5 is the most current (reliable through August 2025). GPT-5 base without web search is weakest (Sept 2024 cutoff). Re-check quarterly.

What if the AI uses “FDII” but cites Cornell LII text that says “FDDEI”?

The regulation-vs-statute asymmetry. The AI correctly retrieves the post-OBBBA statutory text but defaults to the legacy name in its prose. Re-prompt: “use only the terminology in your cited primary sources.” Usually corrects itself; if not, run the output-audit prompt.

What about state conformity?

The secondary trap. Static-conformity states may not have updated their conformity date past July 4, 2025 — meaning OBBBA changes don’t flow through to state income tax for those states. For multi-state returns, add a state-conformity prompt: “List the state-conformity status of [State X] for OBBBA changes as of [date] and identify any provisions where state and federal treatment now differ.” Candidate for a future Specialty-pathway multi-state module.

FDII is now FDDEI: what the OBBBA rename actually changed — the substantive analysis for §250(a)(1)(A)
GILTI is now NCTI: the OBBBA rewrite of §951A — the substantive analysis for §951A
QSBS under OBBBA: §1202’s tiered exclusion — the substantive analysis for §1202
Module S1 — §7216-defensible AI setup — the consent + DPA layer for AI research touching client data
Module S3 — Pre-signature anomaly review — the §10.22 review trail; the rename-trap discipline plugs into S3’s Prompt 5

If you’d rather have the OBBBA rename-trap discipline + prompt library + calibration calendar built into your firm’s AI workflow — including state-conformity tracking and quarterly prompt updates — Tunderman, the publisher of this site, does AI implementation for tax practices. Reach us at editorial@aitaxpractitioner.com.