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GSA7 min readUpdated June 7, 2026

SIN 541211: Auditing Services Guide for GSA MAS

A Refresh 32 guide to GSA MAS SIN 541211, Auditing Services, including category fit, NAICS/PSC context, max order, TDR/OLM status, and offer preparation notes.

Built for
Contractors mapping offerings, pricing support, catalog files, labor categories, or Add SIN modifications to official GSA MAS scope
By the end
Understand where SIN 541211 fits and what evidence to prepare before using it in an offer or modification.
Field guide

When SIN 541211 fits

Scope fit
A close-looking SIN can still be wrong if the subcategory, PSC, NAICS, or deliverable story points elsewhere.
Signal
541211 Perform financial-related audits, performance audits, recovery audits, transportation audits, and contract audits in accordance with Generally Accepted Government Auditing Standards (GAGAS) and non-GAGAS. ^^Financial and Performance audits: Perform an independent assessment of an audited entity's financial statements in conformity with generally accepted accounting principles, financial information, adherence to financial compliance requirements and internal controls, or organization or program performance to identify areas for improvement.^^^^Recovery audits: identify recoverable funds resulting from overpayments, duplicate payments and underpayments under the authority of public law and regulation, e.g., Section 354 of the National Defense Authorization Act for FY 96 (Public Law 104-106; 110 Stat. 268; 10 U.S.C. 2461).^^^^Transportation audits: perform administrative reviews and rate examinations on prepayment and post payment transportation bills to ensure accuracy, completeness, and compliance with established rates, tariffs, quotations, agreements, tenders or other applicable rate authority.^^^^Note: Inherently Governmental services as identified in the Federal Acquisition Regulation (FAR) 7.503 or by the ordering agency are prohibited under this SIN. It is the responsibility of the Contracting Officer placing the order to make this determination. Ordering activities must require prospective contractors to identify potential conflicts of interest and address those, prior to task order award.
Response
Compare the buyer's requirement to the official SIN language before forcing the opportunity into a familiar lane.
Service proof
Service SINs can create labor-category, qualifications, worksite, and rate-support questions.
Signal
The SIN supports service work, labor categories, deliverables, and pricing support.
Response
Prepare labor category descriptions, service narratives, past performance, FCP Services Plus data, and pricing support.
Modification path
Adding a SIN can affect catalog files, service descriptions, pricing support, and buyer-facing records.
Signal
The contractor wants to add this SIN after award or adjust offerings tied to it.
Response
Use the Add SIN and Add Product/Labor Category modification pages to plan scope, price, and evidence changes.
Refresh 32

SIN 541211 quick facts

A compact view of the official SIN record from the user's Refresh 32 MAS offerings workbook.

Category
Professional Services
Financial Services
NAICS
541211
NAICS codes associated with the SIN in the workbook.
PSC
R704
Product Service Code mapped to the SIN.
Max order
$1,000,000
Ordering threshold for seeking additional price reductions.
Part 1

What SIN 541211 covers

541211 Perform financial-related audits, performance audits, recovery audits, transportation audits, and contract audits in accordance with Generally Accepted Government Auditing Standards (GAGAS) and non-GAGAS. ^^Financial and Performance audits: Perform an independent assessment of an audited entity's financial statements in conformity with generally accepted accounting principles, financial information, adherence to financial compliance requirements and internal controls, or organization or program performance to identify areas for improvement.^^^^Recovery audits: identify recoverable funds resulting from overpayments, duplicate payments and underpayments under the authority of public law and regulation, e.g., Section 354 of the National Defense Authorization Act for FY 96 (Public Law 104-106; 110 Stat. 268; 10 U.S.C. 2461).^^^^Transportation audits: perform administrative reviews and rate examinations on prepayment and post payment transportation bills to ensure accuracy, completeness, and compliance with established rates, tariffs, quotations, agreements, tenders or other applicable rate authority.^^^^Note: Inherently Governmental services as identified in the Federal Acquisition Regulation (FAR) 7.503 or by the ordering agency are prohibited under this SIN. It is the responsibility of the Contracting Officer placing the order to make this determination. Ordering activities must require prospective contractors to identify potential conflicts of interest and address those, prior to task order award.

The official record maps this SIN to NAICS 541211 and PSC R704. Those codes are not the whole strategy, but they help explain how the offering is categorized for buyers and reviewers.

Part 2

How to prepare the offer story

For service-oriented SINs, keep the service description, labor categories, pricing support, and past-performance examples aligned. A reviewer should be able to see what work is being sold, who performs it, and why the rate story is defensible.

If the SIN is being added through eMod, write down what changes operationally: new scope, new pricing, new files, catalog impact, and who owns maintenance after approval.

Part 3

Buyer and SEO language to keep straight

Use the SIN number, title, category, and subcategory together: SIN 541211 - Auditing Services - Professional Services - Financial Services. That combination helps a buyer understand the lane quickly and helps the page avoid becoming a vague keyword page.

When writing capability language, explain the actual deliverables and evidence. Do not make the SIN carry the whole message by itself.

Examples

What this looks like in practice

Real-world checkHow to test SIN 541211 before building files

Start with the official title and description: Auditing Services sits under Professional Services > Financial Services. Then compare your actual commercial offering to that scope, not only to the NAICS code.

If the fit still looks strong, build the proof stack: offering description, pricing support, past performance or product support, and any SIN-specific files the current GSA instructions require.

  • Confirm scope language.
  • Check NAICS and PSC signals.
  • Match the pricing file to the offering type.
  • Keep the support package reviewer-friendly.

Frequently asked questions

Is SIN 541211 part of TDR?

The Refresh 32 workbook marks TDR as Y for this SIN. GSA states that TDR became mandatory across MAS SINs with Refresh 31, so contractors should still verify current contract reporting instructions in official GSA sources.

Can order-level materials be used with SIN 541211?

The workbook marks OLM as Y. OLM treatment should always be verified against the current MAS solicitation, mass modifications, and contract-specific instructions.

Should I pick a SIN only because the NAICS matches?

No. NAICS helps, but SIN selection should be based on the actual offering, official SIN description, category/subcategory, pricing files, and buyer acquisition path.