Standard Costing Under GAAP: ASC 330, Variances, and Materiality

Standard costing is acceptable under U.S. GAAP whenever your predetermined costs reasonably approximate actual costs at the balance-sheet date. That single condition, set out in ASC 330-10-30-12, controls the whole system: how often standards get refreshed, how variances are disposed of at period end, and whether the inventory number on your balance sheet will survive an audit.¹

The ASC 330 Rule That Permits Standard Costing

ASC 330 governs inventory measurement. The default rule is that inventory sits on the balance sheet at cost, then gets written down if net realizable value falls below that cost. ASC 330-10-35-1B requires inventory measured under FIFO, average cost, or similar methods to be carried at the lower of cost and net realizable value.¹

The catch is that “cost” normally means what you actually spent, and standard costs are estimates set before production. ASC 330-10-30-12 bridges the gap by permitting standard costs so long as they are “adjusted at reasonable intervals to reflect current conditions” and “reasonably approximate costs computed under one of the recognized bases” at the balance-sheet date. If you use standard costing, the financial statements should describe the relationship, using language such as “at standard costs, approximating average costs.”

The practical takeaway: standard costing is never automatically compliant or automatically disqualified. Your system earns its GAAP status every reporting period based on how close standard lands to actual.

What “Reasonably Approximates” Means in Practice

Three operating conditions have to hold, and auditors will look at all three.

Your predetermined rates for materials, labor, and overhead reflect current market conditions and current operating realities. Standards built on last year’s supplier contracts or outdated production speeds drift from actual costs and eventually fail the test.
Standards reflect attainable performance, with allowances for ordinary scrap, routine downtime, and typical yield losses. Basing standards on theoretical perfection inflates the gap; basing them on known inefficiencies understates true cost.
You run a systematic process for computing, investigating, and disposing of variances each period. Without that, there is no evidence that standards still approximate reality.

If any of these breaks down, the standard cost figures on your balance sheet stop being a reasonable proxy for actual cost, and inventory is misstated.

Using Materiality to Judge the Gap

The dividing line between “close enough” and “needs correcting” is materiality. When the difference between total standard costs and total actual costs would not change a reasonable investor’s view of the financial statements, the standard cost system satisfies GAAP without further adjustment. When it would, adjustment is required.

SEC Staff Accounting Bulletin No. 99 addresses this directly. A 5% threshold is commonly used as a rough screen, and the SEC has said it has “no objection to such a ‘rule of thumb’ as an initial step.” The bulletin also states that “exclusive reliance on this or any percentage or numerical threshold has no basis in the accounting literature or the law.”²

Qualitative factors matter too. A variance under 5% of inventory can still be material if correcting it would turn a reported profit into a loss, trigger or avoid a debt covenant violation, or mask a trend investors would care about. The full test asks whether a reasonable person’s judgment would be “changed or influenced” by fixing the misstatement, based on the total mix of information available.²

Closing Variances at Period End

At the end of each period, variance accounts have to be cleared so the financial statements reflect costs consistent with GAAP. The treatment depends on whether accumulated variances are material, and this is the point where standard cost systems most often go wrong in audit.

Immaterial Variances

When total variances are immaterial, the standard approach is to close every variance account directly into Cost of Goods Sold. Because standard costs already approximate actual costs, spreading the small difference across inventory accounts would not change the financial statements in any meaningful way. A well-maintained standard cost system usually ends up here.

Material Variances

When variances are material, writing them all off to COGS would leave inventory accounts carrying numbers that no longer approximate actual cost, which violates ASC 330. Instead, you prorate the total variance across the three accounts that hold standard costs: Work-in-Process, Finished Goods, and Cost of Goods Sold.

The allocation uses each account’s share of the total standard cost balance at period end. If Work-in-Process holds 15% of that balance, Finished Goods 12%, and COGS 73%, the variance is spread 15/12/73 across them. Unfavorable variances (actual exceeded standard) increase the account balances; favorable variances decrease them. After proration, each account sits closer to actual cost.

Companies that run a clean system all year sometimes treat every variance as immaterial out of habit, without running the quantitative and qualitative analysis SAB 99 requires. If your auditor disagrees with that materiality call, you face restatement risk.

Keeping Standards Current

ASC 330-10-30-12 requires adjustment “at reasonable intervals” without defining a specific frequency, leaving that to judgment. In practice, most companies refresh standards at least annually during the budgeting cycle. For volatile cost categories like commodities or energy, quarterly updates help keep variances from crossing materiality thresholds between annual resets.

Certain events signal that standards need updating before the next scheduled review:

Significant changes in supplier pricing
New labor agreements or wage increases
Shifts in production technology or process changes
Large or persistent unfavorable variances that keep appearing period after period

Ignoring these signals is how a compliant system drifts into noncompliance. By the time variances are big enough to catch an auditor’s attention, a material misstatement may already be sitting on the balance sheet.

How the Tax Side Compares

GAAP compliance does not automatically mean your standard cost system works for tax purposes, though the two sets of rules overlap heavily. Under 26 U.S.C. § 471, inventories must be taken on a basis that conforms to the “best accounting practice” in the taxpayer’s trade or business and most clearly reflects income.³ Treasury Regulation § 1.471-11 lists standard costing as an acceptable method for allocating production costs to ending inventory for manufacturers.⁴

The regulation’s variance rules parallel GAAP with one notable feature. A pro rata portion of net overhead variances and net direct production cost variances must be reallocated to ending inventory. However, if the variances are “not significant in amount” relative to total actual indirect production costs for the year, the reallocation to inventory can be skipped unless it is performed for financial reporting. The IRS gives “great weight” to how you handle variances for GAAP when evaluating the tax method.⁴

One boundary to note: adopting standard costing, or moving away from it, is a change in accounting method for tax purposes. That requires filing Form 3115 with a timely filed return for the year of the change, with a duplicate copy sent to the IRS National Office. Without Form 3115, the IRS has not consented to the change, and adjustments and penalties can follow on examination.⁵

1
FASB. Inventory (Topic 330) – ASU 2015-11
2
U.S. Securities and Exchange Commission. Staff Accounting Bulletin No. 99 – Materiality
3
Office of the Law Revision Counsel. 26 U.S. Code 471 – General Rule for Inventories
4
eCFR. 26 CFR 1.471-11 – Inventories of Manufacturers
5
Internal Revenue Service. About Form 3115, Application for Change in Accounting Method