US federal tax research

Source-linked public research with stated scope and limitations.

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Authority and research method

• Revenue rulings vs. private letter rulings: what tax researchers can rely on

  Classify an IRS document by its publication channel, then state what it supports and for whom, using section 6110(k)(3), the Internal Revenue Bulletin rule, and Rev. Proc. 2026-1.

• What a private letter ruling can and cannot show in your research

  An inference ledger for released IRS written determinations: what the non-precedent rule in section 6110(k)(3) forbids, what a ruling still evidences, and how to convert it into citable authority.

• Temporary, proposed and final Treasury regulations: how to weigh and cite them

  A status check for the 26 CFR text you are about to cite: which class it belongs to, whether a temporary regulation has reached its section 7805(e) sunset, and how far back it can reach.

• Tax Court opinions and the Golsen rule: grading decisions before you cite them

  Grade a tax decision by how it was entered and where an appeal would go, using section 7463, section 7482 venue, IRS examination guidance and the acquiescence program.

• Turning IRS guidance into a citation-checked memo: an authority workpaper

  A four-tier workpaper that sorts Code, regulations, Internal Revenue Bulletin guidance and non-precedential material, and records the exact sentence each source is allowed to support.

Business expenses and capitalization

• Business repairs vs. capital improvements: the §1.263(a)-3 decision sequence

  How Reg. §1.263(a)-3 orders the analysis: fix the unit of property, run the ten enumerated improvement tests, then check the exits and the accounting-method consequence.

• Is it an ordinary and necessary business expense? A four-fork fact checklist

  A fact-intake checklist that routes a claimed §162 deduction through the carrying-on, personal, capital and statutory-disallowance forks, naming the provision that disposes of each.

• The §1.263(a)-1(f) de minimis safe harbor election: conditions, thresholds, limits

  Where the $5,000 and $2,500 figures come from, what the annual election commits a taxpayer to, and the five things the de minimis safe harbor does not do.

• Start-up and organizational costs: the begins-business fork and the deemed election

  Sorting pre-opening spend into the §195, §248, §709(b) and §709(a) buckets, fixing the month business begins, and handling an election the regulations already made for you.

• Business bad debt deductions: the evidence a §166 workpaper has to carry

  The five elements of a §166 write-off in the order an examiner tests them, including the prior-inclusion rule and the charge-off requirement that decide most files.

Depreciation and property

• Section 179 or bonus depreciation: pinning the rule to the acquisition date

  A decision sequence for choosing between section 179 expensing and the section 168(k) allowance, starting with the acquisition-date fork that decides which version of the law applies.

• Placed in service: the evidence that proves readiness and availability

  What the depreciation regulations actually require before an asset is placed in service, and the facts a file needs to fix that date for a specific item.

• Cost segregation studies: what the IRS audit guide expects you to support

  A review checklist built from the IRS Cost Segregation Audit Technique Guide: the thirteen study elements, the report elements, and the classification tests an examiner applies.

• Selling depreciated property: a section 1245, 1250 and 1231 issue map

  An ordering map for the character of gain on a disposition of business property, separating ordinary recapture from the unrecaptured section 1250 rate bucket and the section 1231 netting that follows.

• Section 1031 after the real property limit: eligibility and timing checklist

  Eligibility gates, the two statutory periods, the documentary acts identification requires, and the exposures that outlive closing in a deferred like-kind exchange of real property.

Entity formation and transactions

• Section 351 incorporation transfers: a fact-intake checklist before closing

  A five-step intake checklist for a contribution to a corporation, binding each fact to the provision that consumes it: property, control, boot, liabilities, and the two basis computations.

• Section 338(g) or 338(h)(10): an election issue map for a qualified stock purchase

  An issue map for section 338: whether a qualified stock purchase exists, which of the two elections is available, which party carries the deemed-sale tax, and what the filing rules say.

• Asset purchase or stock purchase: where the federal tax consequences actually diverge

  Which federal issues genuinely turn on deal form: cost basis and the residual-method allocation, whether tax attributes travel under section 381, the written allocation agreement, and Form 8594 reporting.

• Does the transaction qualify under section 368? A qualification sequence

  A working sequence for reorganization qualification: the statutory definition first, then continuity of business enterprise, continuity of interest and the plan of reorganization that carries business purpose.

• Corporate NOLs after an ownership change: a section 382 testing checklist

  Four independent gates under section 382: loss corporation status and the testing date, the more-than-50-percentage-point ownership change test, the limitation amount, and the two-year business continuity rule.

Partnerships

• Testing a partnership allocation for substantial economic effect

  A gate-by-gate review of a section 704(b) allocation: the three economic-effect requirements, the alternate test and qualified income offset, substantiality, and the fallback.

• Outside basis and inside basis: reconciling a partner's two basis figures

  What each basis figure tracks, the Code sections that start and move them, the structural reasons they drift apart, and a workpaper outline that reconciles the two.

• Section 754 election: what to decide before the partnership files

  What sections 743(b) and 734(b) each do, the cases where the election costs the partnership, the adjustments that are mandatory anyway, and the filing and revocation mechanics.

• Disguised sale issue spotting for partner contributions and distributions

  How section 707(a)(2)(B) recharacterizes a contribution paired with a transfer back: the operative test, the two-year presumptions both ways, guaranteed payments, liabilities and disclosure.

• Section 752 liability allocation: recourse, nonrecourse, guarantees and bottom-dollar rules

  A source-linked sequence for allocating partnership liabilities: economic risk of loss, the constructive liquidation, which guarantees and bottom-dollar obligations count, and the three nonrecourse tiers.

Tax accounting and timing

• Cash vs. accrual method: the section 448(c) gross receipts test for 2026

  Who section 448 bars from the cash method, how the gross receipts test is measured, and the inflation-adjusted threshold for tax years beginning in 2026 with the source that sets it.

• Section 451 income timing: the AFS inclusion rule and advance payments

  How an accrual-method taxpayer sequences the section 451(b) financial-statement inclusion rule, the section 451(c) deferral election, and the cost-offset methods in the 2021 regulations.

• All-events test and economic performance: when an accrued liability is deductible

  A routing map for year-end accruals: the three conditions for incurring a liability, which economic performance rule each liability type takes, and the four-part recurring-item gate.

• Form 3115 scoping: automatic changes, non-automatic consent, and section 481(a)

  Scope an accounting-method change before filing: which of the two revenue procedures governs, whether the change is on the current automatic list, and how the section 481(a) adjustment spreads.

• UNICAP under section 263A: exemption, cost categories, and simplified methods

  An issue map for uniform capitalization: whether section 263A reaches the property, who the small-business exemption releases, which costs must be absorbed, and which simplified method is available.

Compensation and benefits

• Reasonable compensation for owner-employees: the C corporation and S corporation forks

  One statutory phrase, two opposite exposures. How IRC 162(a)(1) and Reg. 1.162-7 are applied against C corporation and S corporation owner-employees, and the evidence file both forks need.

• Section 83(b) election: the 30-day deadline, Form 15620, statement contents and forfeiture

  When an 83(b) election must be filed, including section 7503 weekend timing, what the statement or Form 15620 must contain, the copy to the service recipient, the revocation limit, and why forfeiture gives no refund.

• Section 409A issue map: where nonqualified deferred compensation fails

  An ordered issue map for IRC 409A: is there a deferral, was the election timely, is the payment event permissible, does the six-month delay apply, was payment accelerated, and is the failure documentary or operational.

• Fringe benefit exclusions: matching each benefit to its own Code section

  A condition checklist that ties each excludable fringe benefit to the provision that excludes it, keeps the analysis separate for each employment tax, and marks the figures that change by year.

• Worker classification for federal tax: control test, section 530 relief, scope

  A federal-tax-only issue map for employee versus independent contractor: the statutory starting points, the three categories of evidence the IRS publishes, Form SS-8, section 530 relief, and what misclassification costs.

Procedure and controversy

• Notice of deficiency: computing the Tax Court petition period

  How the 90-day and 150-day period in IRC section 6213(a) is counted, what the last date printed on the notice does, and which facts move the deadline.

• Refund claims under section 6511: two clocks and a look-back

  Why a refund claim can be filed on time and still recover nothing: the section 6511 filing periods, the separate look-back ceiling, and the deemed-payment rule.

• Penalty relief evidence: building a reasonable cause file

  Which penalty carries which defense, the order in which administrative and reasonable cause relief are considered, and the documents the IRS says it evaluates.

• Section 274(d) substantiation: adequate records for travel, gifts and listed property

  The heightened records standard for travel, gift and listed-property deductions, the four elements the statute names, and what IRS material allows when records are incomplete.

• Responding to an IRS examination: a document assembly checklist

  How to scope a correspondence exam or Information Document Request, assemble a responsive production, and preserve the procedural rights the Code and the IRM attach.

International federal tax

• US-source vs. foreign-source income: a sourcing fact checklist by income type

  A per-income-type intake checklist for the IRC §861 to §865 sourcing rules: the facts that decide interest, services, rentals and royalties, and sales of property.

• Treaty benefits and Form 8833: when a treaty position must be disclosed

  A decision sequence for IRC §6114 treaty-based return position disclosure: which positions must be reported, which are waived, and the dollar thresholds in the regulation.

• Withholding on payments to foreign persons: the chapter 3 documentation sequence

  A payment-time sequence for IRC §1441 and §1442 withholding: the 30 percent default, what reliable association of documentation means, and what a treaty rate claim requires.

• Is it a CFC? A classification issue map across the 2026 statutory boundary

  An issue map separating the four questions behind CFC status: United States shareholder, CFC, which inclusion regime, and Form 5471 category, with what the 2025 legislation actually changed.

• Form 1118 foreign tax credit limitation: baskets, the 90% rule and carryovers

  A source-linked Form 1118 workpaper sequence for creditability, separate limitation categories, the §904 fraction, the 90% §960 rule, and foreign tax credit carryovers.

Work-product and research methods

• How to structure a source-linked tax memo for a contested deduction

  A seven-block memo architecture for a deduction you expect to be challenged, tied to the written-advice requirements in 31 CFR 10.37 and to what counts as authority.

• Reviewing tax representations in a document: a verification checklist

  A reviewer's method for tax language in an agreement, memo or supporting statement: split proposition from predicate, test currency and periods, and return a fact-intake list.

• Weighing conflicting tax authorities: venue, nonacquiescence and later guidance

  A triage method for two federal tax authorities that point opposite ways: classify the conflict, apply the rules on overruled authority and appellate venue, and record the result.

• Building a federal tax diligence issue list for a business acquisition

  Eight federal tax diligence headings for a target business, each stated as the question, the exposure, the document that evidences it, and the provision that creates it.

• Verifying an AI-generated tax answer against primary authority

  Five checks that take a machine-drafted federal tax answer to a verified one: existence, text match, currency, subsection scope, and whether the authority is still good.