valuation firms specializing in Section 1374 net unrealized built-in gain determinations at C-to-S conversion

Section 1374 exists to close a loophole Congress spotted decades ago: without it, a C corporation could elect S status, sell its appreciated assets, and pay only one layer of tax instead of two. So Congress built a corporate-level tax, at 21% on net recognized built-in gain, that applies for a five-year window after the conversion date. That window, made permanent by the PATH Act of 2015 for tax years beginning on or after January 1, 2015, is still the operative rule in 2026. The whole system, though, hinges on a single figure calculated once and never revisited: net unrealized built-in gain, or NUBIG.

NUBIG is the fair market value of every corporate asset as of the first day of the S election, minus the aggregate adjusted basis of those assets, as defined under IRC §1374. Treasury regulations translate this into a concrete exercise: a hypothetical sale of all corporate assets at fair market value, on that one day. Not a projection, not a range. A snapshot, taken once, that governs everything downstream of it.

That snapshot becomes a ceiling. If NUBIG comes in at $1,150,000 on the conversion date, no more than $1,150,000 can ever be taxed under §1374, across the full five-year recognition period, no matter what actually sells or when. A tighter, more defensible NUBIG figure lowers that ceiling permanently. An inflated or sloppy one locks the corporation into a bigger tax bill for years it hasn't even lived through yet.

Treating the NUBIG appraisal as a formality to check off before filing the election is the single most expensive mistake a practitioner can make. It happens constantly, and it happens for a boring reason: nobody recalculates this number later, so whatever error gets baked in on day one rides along for five years untouched, compounding in silence until an exam surfaces it. Firms that rush this step to close the conversion faster aren't saving anyone time. They're moving the cost downstream and betting nobody looks closely enough to catch it.

Built-in losses cut the other way, and get overlooked just as often, which is the mistake worth naming plainly here: appraisers told to find gain rarely go looking for its opposite, because nobody told them to. Assets sitting below adjusted basis on the conversion date generate built-in losses, which offset built-in gains recognized in the same year, inside the same five-year window. An appraisal that only hunts for gains and skips undervalued assets leaves real tax relief on the table. The annual cap, net recognized built-in gain, is the lesser of recognized built-in gains net of losses or the corporation's overall taxable income for that year, and any excess gain in a loss year carries forward within the recognition period. NOL and capital-loss carryforwards from the C-corp years can offset this figure too, under §1374(b)(2), but only if the valuation firm's underlying work ties out cleanly enough for the offset to survive an exam.

Skip the appraisal altogether, and the IRS doesn't leave the vacuum empty. Under §1374(d)(3), any gain recognized during the recognition period is presumed to be built-in gain unless the corporation proves otherwise. No contemporaneous valuation means no evidence to rebut that presumption, and the agency is free to treat the full gain on a later sale as built-in, regardless of what actually happened economically at conversion.

The asset classes where valuation errors concentrate

Real estate and equipment sound simple: fair market value against adjusted tax basis, as of one date. In practice it requires licensed appraisers who know the local market, not a generic multiple pulled from a database. Errors here are usually errors of comparables rather than concept, which makes this the easiest category to get right, provided the firm bothers to hire someone who actually walks the local market instead of running a desktop estimate off a spreadsheet.

Inventory is where the technical standard trips people up, and it trips up more firms than it should. The applicable Treasury regulations require a bulk-sale valuation for inventory: what the entire inventory would fetch sold as a block, not retail selling price and not replacement cost. A firm that defaults to either of those produces a NUBIG figure that doesn't meet the regulatory standard, full stop, and no amount of careful math elsewhere in the report fixes that. LIFO inventory compounds the problem, since old layers can hide a built-in gain of real size. Someone has to walk through the layers individually rather than take the balance sheet figure at face value.

Cash-basis accounts receivable are an easy miss. Unbilled receivables sitting on the books at conversion become built-in gain once collected during the recognition period, but an appraiser who treats them as a routine accounting line item rather than a §1374 asset can walk right past them.

Intangibles beyond goodwill (customer lists, trade names, technology, non-competes, backlog) all need separate identification and separate valuation. RSM's guidance on this point is blunt: the taxpayer carries the burden of showing each intangible has value that's readily ascertainable, separate and distinct from goodwill, and tied to a determinable useful life. A valuation built for financial-statement purposes or for an M&A deal will often fail this test even when the underlying numbers are accurate, because nobody ever asked it to satisfy that standard. This is a reason to review any pre-existing valuation before leaning on it for §1374 purposes.

Enterprise goodwill deserves its own paragraph, because it's the asset most often missed entirely, and it's usually the largest number on the page once someone finally looks for it. It frequently carries a basis of zero and a value in the millions, especially in service businesses built on relationships and reputation. Bound up in it is the question of personal goodwill, which belongs to the individual, not the corporation, and therefore isn't a built-in gain asset at all. The IRS will challenge any bifurcation between personal and enterprise goodwill that isn't backed by a contemporaneous, defensible appraisal. This is not a line item to eyeball and move past.

Two more mechanics round out the list. Under the §1374 regulations, gain from a built-in gain asset sold on installment terms within the recognition period stays subject to BIG tax even if the actual payments land after the five years expire, so the appraisal has to flag assets likely to be sold that way. And where an S corporation holds interests in other entities, the valuation work may need to extend beyond the corporate level to capture the full built-in gain exposure accurately.

The regulatory methodology firms must follow, and the judgment calls within it

Treasury and the IRS settled on an aggregate approach for NUBIG, sometimes called the "1374 approach": the corporation is treated as if it sold all of its assets in one hypothetical transaction, rather than valuing every item of income and deduction separately. That hypothetical-sale framework, laid out in Treas. Reg. §1.1374-3, isn't unique to §1374 either. It's cross-referenced in the §382 loss-limitation regulations, which means a firm with §382 ownership-change valuation experience already has structural familiarity with the same mechanics.

Carryover-basis acquisitions add a wrinkle worth flagging on its own. Under the §1374 regulations, assets acquired from a C corporation in a carryover-basis transaction require a separate NUBIG determination, running on its own recognition period from the acquisition date, entirely apart from the five-year period governing the electing corporation's own assets. A firm unfamiliar with this provision may fold everything into one pool, and that's simply the wrong answer. A blended pool understates or overstates exposure on both sets of assets at once, and there's no clean way to unwind it after the IRS catches it on exam.

Judgment enters even within the aggregate framework. Nothing forces a single rigid technique for allocating enterprise value across asset classes, but if the IRS challenges the allocation, it has to hold up asset by asset. The firm's methodology memo, more than the final number, is what does the defending. Inventory is a good example: the regulations mandate the bulk-sale standard but don't hand the appraiser a specific technique, so the firm has to choose one appropriate to the industry and document why. Goodwill allocation runs into the same issue in a sharper way, because the personal-versus-enterprise split needs an explicit, supportable methodology behind it. A vague allocation, one that reads like a plug number, is the first thing an examiner goes after.

What credentials and qualifications actually signal §1374 competence

Look for the standard business valuation credentials: Accredited Senior Appraiser (ASA) from the American Society of Appraisers, or Certified Valuation Analyst (CVA) from NACVA. These designations require demonstrated competence in valuation work generally. Treating any one of them as proof of §1374 fluency is the mistake most people make when hiring, and it deserves to be said plainly: a credential is a floor, not a specialty.

A generalist with an ABV may never have handled the hypothetical-sale framework, never applied the bulk-sale inventory standard, and never worked through a personal-versus-enterprise goodwill bifurcation. A firm that leads with its letters after the name rather than its §1374 engagement history is, more often than not, the weaker choice, and clients who hire on credential alone tend to find that out during an exam rather than before one. That's exactly the wrong time to discover it.

Multi-asset coordination matters just as much. A single NUBIG engagement typically spans real estate, equipment, intangibles, and goodwill, asset classes that often call for different appraisers with different specialties. Ask directly whether the firm handles that coordination in-house or subcontracts pieces out, and how the final report reconciles the components into one number. A patchwork of disconnected valuations stitched together at the end is a weaker product than one built by a team working from a single methodology from the start, and it shows up on exam the same way a poorly sourced footnote shows up in an audit: as the first thing pulled apart.

Tax-specific experience is its own filter, separate from valuation credentials entirely. The appraiser should know IRS exam procedure, the Treasury regulations under §1374 specifically, and the documentation standards that hold up under scrutiny. A valuation prepared for financial reporting or M&A purposes won't automatically clear the §1374 evidentiary bar, even when the math is sound, because it wasn't built to answer the questions an examiner will ask.

State conformity is worth a separate question for clients outside the federal baseline. Some states don't conform to the PATH Act's five-year recognition period. Others may conform only partially or revert to a longer period. A firm working with clients in either state needs explicit familiarity with the state-level BIG rules, because the federal appraisal alone won't answer the state exposure question.

And the deliverable itself should look like an appraisal report, not a summary letter. Every asset valued, the methodology applied to each one, the basis and FMV conclusions, and a reconciliation to the final NUBIG number: that's the document that lands on an examiner's desk if the return gets pulled.

IRS-defensibility as a selection criterion separate from technical accuracy

A technically accurate valuation that can't survive examination hasn't done its job. Firms get hired on the wrong criterion constantly: the number looks right, so the report must be sound. That reasoning runs backwards. Under §1374(d)(3), the burden sits with the taxpayer, and any gain recognized during the recognition period is presumed built-in unless the S corporation proves otherwise. The NUBIG appraisal is the primary evidence offered to rebut that presumption, which makes defensibility a selection criterion in its own right, distinct from whether the numbers are correct.

Timing is the first defensibility test. An appraisal commissioned years after conversion, after the IRS has already started asking questions, carries far less weight than one dated to the conversion itself. The firm needs to be engaged before or at the time of the S election, not after a notice arrives, and there's no fixing that sequencing after the fact.

Report quality is the second test. A narrative-supported appraisal, consistent with USPAP standards and backed by documented market data and stated methodology, is a different category of document from a two-page summary letter or a spreadsheet of numbers with no explanation attached. Asking a firm for a redacted sample report from a comparable engagement is a reasonable, and revealing, request.

Institutional memory of IRS exam behavior is the third test. A firm whose principals have represented clients through actual examination or appeals on §1374 issues knows where examiners tend to dig: goodwill allocation, inventory methodology, and intangible asset identification come up again and again. RSM's language on the intangibles separateness test captures how high that bar sits, describing the taxpayer's burden as perhaps extremely difficult, drawing on court language, to establish that an intangible has value separate and distinct from goodwill and is tied to a determinable useful life. The report has to meet that standard for every single intangible claimed, not gesture at it in the aggregate.

Personal goodwill deserves the same rigor. A defensible bifurcation needs contemporaneous support tying specific capabilities, relationships, and reputation to the individual rather than the entity. Firms that routinely handle owner-compensation studies and personal-goodwill analyses tend to be better positioned here than generalist appraisers encountering the question for the first time.

Firms confirmed to offer §1374 NUBIG valuation services

Grossman Yanak & Ford LLP, based in Pittsburgh, lists IRC §1374 built-in gain analysis explicitly among its business valuation services, alongside marital dissolution valuations, M&A work, solvency opinions, and shareholder dispute engagements. That breadth suggests a valuation practice built around a range of engagement types rather than a shop that only does §1374 work occasionally.

Exit Strategies Group, Inc., headquartered in Petaluma, California, describes §1374 valuation as the mechanism that establishes tax basis for corporate assets at the time of the S election, and its service materials walk through the five-year built-in gains exposure window directly. The firm has operated since 2002, focused on business sales, acquisitions, valuations, and exit planning for family-owned and closely-held companies. Its California base is relevant beyond geography: California doesn't conform to the federal five-year recognition period, so clients working with a California-based firm are dealing with an active state-level question that a firm outside the state might not surface unprompted.

The CBB Group, based in Oregon, also confirms §1374 valuation as a service area, describing the need for a valuation when an existing C corporation converts to subchapter S status, in order to establish tax basis for corporate assets as of the election date.

Beyond these three, the framework built out above doubles as a screening tool for any other firm under consideration. Run the credentials screen: what designations do the lead appraisers hold, and how much of their §1374 work actually spans multi-asset, multi-class engagements versus single-asset jobs. Run the methodology screen: does the firm document the aggregate hypothetical-sale approach under Treas. Reg. §1.1374-3, and does the final product read as a full appraisal report rather than a summary. Run the defensibility screen: has the firm supported §1374 positions through actual IRS examination, and can it show, concretely, how it handles the intangibles separateness burden and the personal-versus-enterprise goodwill split.

How the tax professional overseeing the conversion fits into the valuation firm relationship

The tax practitioner running the conversion doesn't perform the appraisal, but the quality of the appraisal depends heavily on how well that practitioner briefs the valuation firm. That means handing over a full asset inventory, adjusted basis schedules, the corporation's accounting method, its state of domicile, any dispositions planned within the five-year recognition period, and flagging any carryover-basis acquisitions that trigger a separate NUBIG pool under §1374(d)(8). Miss one of those inputs, and the valuation firm is working blind on a piece of the puzzle it never knew existed.

Timing sits with the practitioner too. The appraisal needs to be ordered before or at the same time as the S election filing, because a retroactive valuation, ordered after the fact, carries less evidentiary weight if the return ever gets examined. Waiting until there's a reason to worry is waiting too long, and by the time a notice shows up, the window to fix it has already closed.

Before the report goes final, the practitioner's job is to check it against the regulatory framework line by line: confirm inventory uses the bulk-sale standard rather than retail or replacement cost, confirm every intangible is separately identified with useful-life support attached, and confirm personal goodwill is bifurcated with documentation that would hold up if an examiner asked for it. The valuation firm brings the technical appraisal skill. The tax professional is the one who knows whether that appraisal actually answers the legal questions §1374 is going to ask five years from now.