Stained Glass Studio Bookkeeping: ASC 606 Milestone Billing, OSHA Lead Compliance, and Historic Preservation Tax Credits

A single ecclesiastical restoration commission can span three years, involve six figures of qualified rehabilitation expenditure, and require coordination with a state historic preservation office, an OSHA-mandated blood-lead monitoring program, and a parish committee that meets quarterly. Yet many solo artisan glaziers still try to manage the whole financial side with a shoebox of invoices and a spreadsheet labeled "Smith Window Final.xlsx."

Stained glass is one of the oldest continuous trades in North America, and one of the most financially complex small businesses you can run. The work happens in slow phases — cartoon approval, glass cutting, leading, cementing, installation — that can stretch across fiscal years. The materials are simultaneously hazardous, expensive, and subject to multistate tax rules. The customers range from a hobbyist buying a $40 panel kit to a diocese spending $400,000 on a multi-year cathedral window restoration. And the regulatory environment, sitting at the intersection of OSHA lead standards, EPA hazmat disposal, and historic preservation tax law, leaves no room for sloppy records.

This guide walks through how artisan glaziers, restoration studios, and architectural leaded glass shops can structure their bookkeeping to survive an audit, qualify for tax credits, and actually understand what they earn per square foot.

Why Stained Glass Bookkeeping Is Different

Most small craft businesses fit into one of two accounting molds: a retail shop selling inventory, or a service business billing hours. A stained glass studio is neither. It's a hybrid that pulls revenue from at least five distinct streams, each with its own recognition timing under ASC 606:

• Commission-built custom windows — typically a long-form project with milestone billing tied to physical phases of work
• Ecclesiastical restoration of historic windows — often multi-year, frequently funded with tax credits, almost always requiring documented preservation methods
• Wholesale lampshade and decorative panel production — point-of-sale revenue with COGS based on standard costing
• Glass-cutting classes and workshops — tuition income, often paid upfront, that should be deferred until the class actually meets
• Retail hobbyist supply sales — straightforward retail with inventory tracking and multistate sales tax exposure

A studio that treats all of these as a single revenue line will lose sight of which segment is actually profitable. In our experience working with artisan studios, the classroom side often subsidizes the commission side, and most owners are shocked to learn this.

The five-step ASC 606 framework, in plain glass-shop language

ASC 606 reduces to five questions for any contract:

1. Is there a contract? A signed commission agreement, a parish purchase order, a workshop registration — each is a contract under ASC 606.
2. What are the performance obligations? A cartoon design, the fabricated window, the on-site installation, and any post-installation warranty service may each be distinct.
3. What's the transaction price? This includes the base fee, any retainer, change orders, and any pass-through expenses you control.
4. How is the price allocated? If your $80,000 commission includes design ($5,000), fabrication ($65,000), and installation ($10,000), each gets recognized separately.
5. When is revenue recognized? Either at a point in time (when the panel is delivered) or over time (as cartoon, cutting, leading, and installation phases complete).

For long-form architectural work, "over time" recognition using an input method — typically labor hours or costs incurred relative to total estimated costs — is usually the right answer.

Milestone Billing for Multi-Year Commissions

A typical commission contract for a 12-foot ecclesiastical window might break out like this:

Each milestone, when reached, transfers control of a distinct part of the work — and that's the ASC 606 trigger to recognize revenue. Until then, payments received are deferred revenue (a liability), not income, and costs incurred are work-in-process (an asset), not expense.

This matters enormously at year-end. A studio with $200,000 of in-progress commissions can show very different P&L outcomes depending on whether it correctly applies milestone recognition or simply books cash as it comes in. Cash-basis accounting may technically be available to studios under the small-business gross-receipts threshold, but accrual treatment usually produces a more honest picture of profitability — and is often required if you want to claim certain tax credits.

Restoration Projects and the Historic Preservation Tax Credit

When you restore stained glass in a certified historic structure, your client may be claiming the 20% federal Rehabilitation Credit under IRC Section 47. The credit equals 20% of "qualified rehabilitation expenditures" and is allocated ratably over five years on the building owner's return. Your invoices may be exactly those expenditures.

What this means for your bookkeeping:

• Document everything by line item. "Restoration services" on a single $48,000 invoice is far less useful than a breakdown of cartoon documentation, glass procurement, leading, cementing, installation, and travel. The owner's preservation consultant will ask for backup; the National Park Service's certifying office may too.
• Photograph and date your work product. Before, during, and after photos are not just marketing assets — they're evidence that the work was done to the Secretary of the Interior's Standards for Rehabilitation, which is what the credit requires.
• Distinguish capital from operating expenditures on the client's side. Routine maintenance (cleaning, re-puttying a few loose pieces) is not a qualified rehabilitation expenditure. A full panel re-lead with documented preservation methodology often is. Helping your client understand this distinction protects the credit they're banking on.
• State credits stack. Many states — Iowa, Texas, Illinois, Kansas, Michigan and others — offer their own historic preservation credit that can be combined with the federal credit. Your client's accountant will appreciate invoices structured to make state credit applications easier.

Inventory and Section 263A: When Glass Becomes WIP

Sheet art glass, lead came, copper foil, solder, and cementing compound start their life as raw materials. Once you cut a sheet into a window's pieces and begin leading them up, that glass is no longer a raw material — it's work-in-process. And work-in-process on long-form contracts is subject to Section 263A UNICAP (uniform capitalization) rules if your average gross receipts exceed the small-business threshold (currently around $30 million, indexed annually — but small studios should still understand the concept).

Even sub-threshold studios benefit from cleanly separating:

• Raw materials inventory — sheet glass, came stock, foil rolls, solder spools, cement compound
• Work-in-process inventory — partially completed commissions, with labor and overhead allocated
• Finished goods inventory — completed lampshades, decorative panels, and stock items awaiting sale
• Retail merchandise — hobbyist supplies bought for resale

The first three categories carry standard costing methodology and overhead allocation; the last is a straight retail margin calculation. Mixing them obscures your real margins and makes year-end inventory counts a nightmare.

OSHA Lead Compliance and What It Costs You

Lead exposure is the single biggest regulatory risk a stained glass studio faces, and the bookkeeping side often gets overlooked. Under OSHA 29 CFR 1910.1025, employers must keep employees below 50 µg/m³ airborne lead concentration averaged over an 8-hour period, with an action level of 30 µg/m³ that triggers exposure monitoring and medical surveillance.

For a working studio, this typically means recurring costs you should track as separate expense categories:

• Industrial hygiene monitoring — periodic air sampling, typically quarterly or annually depending on your work volume
• Blood-lead testing — for any employee exposed at or above the action level, with documented baseline and follow-up samples
• Personal protective equipment — respirators, disposable coveralls, gloves, with documented fit testing
• Engineering controls — local exhaust ventilation at soldering and leading stations, with documented maintenance
• Hazmat disposal — spent solder, lead came scrap, contaminated rags, all subject to EPA hazardous waste handling

These aren't just compliance costs. Properly capitalized, your ventilation system, fume hoods, and HEPA-filtered vacuum equipment are Section 179-eligible assets that reduce taxable income in the year placed in service. Track them as fixed assets, not supplies.

Capitalizing Studio Equipment Under Section 179

Most studio buildouts qualify for Section 179 expensing, which for 2026 allows up to $1,250,000 of qualifying property to be expensed in the year placed in service (with bonus depreciation continuing its phase-down). Items worth capitalizing as fixed assets rather than expensing as supplies include:

• Kilns for fused and slumped glass work
• Sandblast cabinets
• Soldering stations with integrated fume extraction
• Diamond glass cutters and ring saws
• Came-stretching jigs and benders
• Custom light tables and easels
• Heavy-duty studio HVAC and dust collection
• Studio leasehold improvements when permanent

For studios in older industrial buildings, a cost segregation study on a major buildout can re-classify portions of the work into shorter recovery periods, accelerating depreciation deductions in early years.

Worker Classification: W-2 Apprentices vs. 1099 Restoration Subcontractors

Stained glass studios commonly bring in outside help for two very different purposes: studio apprentices learning the trade, and specialized restoration subcontractors hired for a specific scope. The classification analysis is different for each.

A studio apprentice who comes to your shop on a regular schedule, uses your tools, follows your work direction, and is paid hourly is almost certainly a W-2 employee under both the 2024 DOL Final Rule and the various state ABC tests (California's AB5, Massachusetts, New Jersey, etc.).

An independent restoration specialist who brings their own tools, sets their own hours, is hired for a defined deliverable, has their own insurance, and works for multiple studios may legitimately be 1099. The key documentation: a written subcontractor agreement, their certificate of insurance on file, their own business license, and invoices that look like a business-to-business transaction.

Misclassification penalties at both the federal and state level have grown sharply in recent years. When in doubt, classify as W-2. The savings from a 1099 designation rarely justify the back-pay, back-tax, and penalty exposure if a state labor board disagrees.

Insurance Coverage Your Studio Actually Needs

A general business liability policy is the floor, not the ceiling. Stained glass operations should also carry:

• Inland marine coverage — for client-owned restoration pieces in your custody, in transit, or temporarily at a job site. Standard property policies typically exclude these.
• Tools-of-trade coverage — for studio equipment temporarily off-premises for installation work
• Errors-and-omissions — for design and consultation services, particularly on landmark work
• Workers' compensation — mandatory in nearly every state for any W-2 employee, with lead-exposure rating that affects premiums
• Climate-stress and breakage warranty reserve — not insurance per se, but a balance sheet liability you accrue against historical claims rates

Track insurance premiums by category, not as a single line. When a claim happens, you'll want to know exactly which policy responded and what the loss ratio looked like.

The KPIs Studio Owners Should Actually Watch

The Stained Glass Association of America publishes benchmark data its members can reference, but every studio should track its own version of the same metrics:

• Studio net multiplier — total project revenue divided by direct labor cost. A healthy commission studio typically runs 2.7x to 3.5x; restoration work tends to run lower because materials are a larger share of the budget.
• Realization rate — billed hours divided by worked hours on a job, then multiplied by the ratio of collected dollars to billed dollars. This catches both estimation errors and collection problems.
• Square-foot pricing — your average revenue per square foot of completed glass, segmented by commission vs. restoration vs. retail
• Work-in-process aging — the dollar value and age of open commissions. A piece that's sat at "leading complete, cementing not started" for six months may have a client communication problem you don't know about.
• Backlog months — signed commissions divided by monthly revenue capacity. Most healthy artisan studios run between three and twelve months of backlog.
• Class fill rate and revenue per seat-hour — for the education side of the business

Run these monthly. A studio that only looks at its books at tax time is flying blind through 12 months of cash flow.

Keep Your Studio Finances Organized from Day One

Stained glass is craftsmanship that compounds in value over decades — and your books deserve the same long-term thinking as the windows you build. Whether you're tracking a multi-year ecclesiastical restoration, allocating studio overhead across commissions, or documenting qualified rehabilitation expenditures for a client's tax credit, having clean, version-controlled financial records is essential.

Beancount.io provides plain-text accounting that gives you complete transparency and control over your studio's financial data — no proprietary file formats, no vendor lock-in, no black-box month-end magic. Your books become a permanent, auditable record you actually own. Get started for free and see why developers, artisans, and finance professionals are switching to plain-text accounting. For the technically curious, the docs walk through how a stained glass studio might model commission WIP and restoration billing in Beancount's double-entry format, and the Fava dashboard gives you a live view of your numbers without leaving plain text behind.