A custom home builder once told me his company had "made money on every job" for three years running. Then his accountant ran the numbers under the percentage-of-completion method, and the picture changed entirely. Two of his largest jobs—both still open at year-end—had quietly slid into loss positions because change orders piled up faster than allowances, and nobody was tracking phase-level variance until close-out. The cash was still coming in from progress draws, but the underlying margin had been bleeding out for months.
This is the central problem of residential general contracting: jobs run for nine to eighteen months, money flows in waves of draws and retainage, and the difference between a profitable year and an underwater one often comes down to whether your books told you the truth in month four instead of month fourteen. Custom home builders who treat bookkeeping as an after-the-fact tax exercise routinely discover problems too late to fix them. Those who treat job costing as a live operational system catch margin erosion while they can still recover.
This guide walks through how independent GCs and custom home builders should structure their books: which tax method to choose under Section 460, how to set up job cost categories, how to handle deposits and retainage, what to reserve for warranty exposure, and which KPIs the NAHB benchmark cohort actually uses.
Choosing Your Income Tax Method Under Section 460
Long-term construction contracts—any contract not completed within the same tax year it began—are governed by Internal Revenue Code Section 460. The default rule requires the percentage-of-completion method (PCM), which forces builders to recognize income as costs are incurred rather than when the contract closes. PCM smooths income but accelerates tax liability into the construction period, often well before the homeowner pays the final draw.
Two important exceptions matter for residential builders.
The Home Construction Contract Exemption
Contracts where 80 percent or more of estimated total costs are attributable to building, reconstructing, or rehabilitating dwelling units in buildings containing four or fewer units qualify as "home construction contracts" under Section 460(e)(1)(A). These contracts are exempt from PCM regardless of contract length or company size. A custom home builder constructing single-family homes, duplexes, triplexes, or fourplexes can use the completed-contract method (CCM), the cash method, or the accrual method—whichever produces the best result given the company's cash flow and tax planning needs.
For most custom builders, this means CCM is on the table. Under CCM, all revenue and cost recognition is deferred until the job is "substantially complete," which generally means the home is ready for occupancy and the customer has accepted it. The advantage is tax deferral. The disadvantage is that GAAP financial statements still require PCM-style accrual reporting for banks and bonding companies, so you may end up keeping two sets of books.
The Small Construction Contract Exemption
For non-residential or mixed-use contracts that fall outside the home construction exemption, the small contractor exception under Section 460(e)(1)(B) provides relief. The 2025 One Big Beautiful Bill Act expanded this exception meaningfully. Previously, the exception applied only to contracts expected to be completed within two years, and only if the contractor's average annual gross receipts for the prior three years stayed under the inflation-indexed threshold (currently around $31 million). Under the revised rule, contracts expected to be completed within three years now qualify, expanding the exception to a much larger universe of mid-size residential developers and remodeling firms.
If you're below the gross receipts cap and your contracts are short enough to qualify, you can elect CCM, the cash method, or the exempt-contract percentage-of-completion method for those jobs.
Practical Recommendation
Most custom home builders should adopt CCM for tax reporting on home construction contracts and an accrual-with-job-cost system for management reporting. The tax election is filed with Form 3115 if you're changing methods, and once made, it generally applies to all contracts of that category. Talk to a CPA before electing, because the choice interacts with depreciation, lookback interest, and the alternative minimum tax in ways that aren't obvious from the statute.
Setting Up Job Cost Categories
The single biggest determinant of bookkeeping quality for a residential GC is the job cost structure. Done well, you can see margin erosion at the phase level in near-real-time. Done poorly, you discover problems six months after they were fixable.
A sensible chart of accounts for custom home building separates direct costs into distinct phases that map to the natural construction sequence. Lot acquisition and site work runs roughly 10 to 15 percent of total cost and includes lot purchase, demolition, clearing, excavation, and rough grading. Foundation typically lands between 5 and 10 percent and covers footings, slabs, foundation walls, waterproofing, and underslab plumbing rough-in. Framing and shell, the largest single line item, consumes 15 to 20 percent of the budget and includes lumber, trusses, sheathing, roofing, windows, and exterior doors. MEP rough-in—mechanical, electrical, and plumbing—runs 10 to 15 percent. Drywall, insulation, and interior trim sit around 8 to 12 percent. Finishes, including flooring, paint, cabinetry, countertops, and tile, often run 20 to 30 percent because this is where homeowner specifications drive the most variation. Fixtures, appliances, and final mechanical trim add another 5 to 10 percent. Soft costs—permits, plan review, architectural fees, construction loan interest, and project management labor—round out the remaining 5 to 10 percent.
Each phase needs both a budget and an actual column, with variance calculated and reviewed weekly during active construction. If framing was budgeted at $48,000 and actuals are at $58,000 with the deck not yet built, the project manager needs to know in week seven, not at close-out.
Track each subcontractor invoice against the phase it relates to, not just the trade. A plumbing invoice for rough-in goes against MEP rough-in; the same plumber's invoice for finish fixtures goes against fixtures and trim. This separation makes margin attribution honest.
Change Orders, Allowances, and Owner-Directed Selections
Change orders are where custom builder margin lives or dies. The contract usually establishes allowances for owner-selected items—cabinets, countertops, lighting, tile, flooring—and any selection that exceeds the allowance generates a change order. Selections that come in under the allowance generate a credit, though some builders structure their contracts to retain the underrun as upside.
Every change order should be its own subledger entry with three components: the actual cost of the changed work, the builder's markup (typically 15 to 25 percent on cost-plus jobs, sometimes higher on smaller change orders to cover transaction overhead), and a written approval from the homeowner before the work begins. If you do the work first and chase signatures later, you'll lose collection battles. Build a discipline that no change order moves to construction without a signed authorization, and post the change order to the job cost ledger the day it's approved.
Allowances themselves should sit on the balance sheet as a separate liability or contra-asset until the actual selections are made and reconciled, because the contract revenue is fixed but the actual costs are still floating. At close-out, true-up the allowances against actuals and book the net difference to the appropriate revenue or cost line.
Customer Deposits and Retainage
Residential construction contracts almost always involve customer deposits at the start and progress draws throughout the build. These are not revenue when received. Under both GAAP and the home construction CCM tax method, customer deposits are unearned revenue and sit on the balance sheet as a liability until the corresponding work is performed (under accrual reporting) or until substantial completion (under CCM).
A typical custom home contract draws against milestones: 10 percent on signing, 15 percent on foundation, 20 percent on rough-in, 20 percent on drywall, 20 percent on finish, and 15 percent at substantial completion. For accrual-method management reporting, recognize revenue as costs are incurred on a percentage-completed basis. For tax reporting under CCM, defer everything to close-out.
Retainage works in the opposite direction. When you bill the bank or the homeowner under a construction loan, the lender typically retains 5 to 10 percent of each draw as security against punch list and quality issues. That retained amount is still earned revenue—you've performed the work—but it's a receivable that won't be collected until substantial completion and final inspection. Set up a separate balance sheet line for retainage receivable, and age it independently from regular AR. Banks sometimes hold retainage for 30 to 60 days past substantial completion, so cash flow planning needs to account for the gap.
On the payable side, you'll typically retain 5 to 10 percent from your own subcontractors, mirroring what the bank holds from you. That subcontractor retainage payable sits as a liability until you release it after their work passes final inspection.
Mechanics Liens and Lien Waivers
Mechanics lien law is state-specific, and the procedural traps are unforgiving. Each state has its own notice, filing, and waiver requirements, and missing a deadline usually destroys the lien right entirely. As a general contractor, you generally have direct contract privity with the owner and don't need preliminary notice in most states, but your subcontractors and suppliers do, and their lien rights can attach to the property even after you've paid them.
The defensive structure looks like this: every subcontractor and supplier payment is contingent on receiving a signed conditional or unconditional lien waiver for the amount paid. Conditional waivers become effective only when the check clears; unconditional waivers are enforceable on signature. Pay with conditional waivers, then collect unconditional waivers after the funds settle.
In Texas, residential projects require the GC to provide the owner with a disclosure statement and a list of subcontractors and suppliers unless waived in writing. Notice deadlines for retainage claims fall on the 30th day after contract completion, termination, or abandonment. In Nevada, a notice of intent to lien must precede the lien filing by at least 15 days. In Ohio, subcontractors and suppliers must file a Notice of Furnishing. Every state is different.
Keep a lien waiver log per job, organized by subcontractor and pay period. At close-out, the absence of any executed waiver should block final payment until resolved, because that's where double-payment risk lives.
Warranty, Callback, and Habitability Reserves
The single most underappreciated balance sheet item for custom home builders is the warranty and callback reserve. Industry standard warranty structures provide one year on "fit and finish" items (paint, trim, drywall, cosmetic finishes), two years on delivery systems (HVAC, plumbing, electrical), and ten years on structural elements (framing and foundation). Beyond these contractual warranties, the implied warranty of habitability—recognized by courts in every state—holds builders to a strict liability standard for latent defects that render a home unfit for habitation. Several state supreme courts have ruled that this implied warranty cannot be waived even by written agreement.
What does this mean for your books? You need a real reserve, not a placeholder. The most common approach is to accrue a percentage of revenue—typically 0.5 to 2 percent—into a warranty liability account at the time of substantial completion. The actual charge-off rate varies by builder, but builders who track callback frequency and per-incident cost will quickly converge on their true rate within a few years of operation. A reserve that's chronically underfunded is a sign that quality control upstream is failing; a reserve that's chronically over-accrued just delays profit recognition.
The ten-year structural exposure is harder to reserve because the events are rare but catastrophic. Most builders cover this with a third-party structural warranty product (sold by companies like 2-10 Home Buyers Warranty, Bonded Builders, or RWC) and treat the warranty premium as a closing cost on each home. Even with third-party coverage, professional liability and general liability insurance are essential, with construction defect coverage explicitly included or excluded depending on the carrier.
Accurate bookkeeping from day one prevents tax headaches later, and disciplined warranty reserving prevents the kind of multi-year cash flow shock that ends builder businesses when a development goes bad three years after handover.
NAHB Benchmark KPIs
The NAHB's annual Cost of Doing Business Study is the single best benchmark source for residential builders. Recent surveys put the average single-family builder at a 20.7 percent gross profit margin and an 8.7 percent net profit margin, with the spread between the two representing overhead and SG&A.
Several KPIs deserve weekly or monthly attention.
Gross profit per square foot, computed as (contract price minus direct construction costs) divided by finished square footage, normalizes profitability across different home sizes. For builders in 2026, custom home construction commonly runs $400 to $700 per square foot in many markets, with semi-custom $325 to $550 and production homes $180 to $310. Knowing where you sit lets you compare like-for-like jobs.
Markup percentage versus margin percentage is a chronic source of error. A 25 percent markup on cost produces a 20 percent margin on price. A 33 percent markup yields a 25 percent margin. Get this wrong on the bid and you've underpriced your work by hundreds of basis points.
Cycle time per phase—days from foundation pour to framing dry-in, dry-in to mechanical sign-off, mechanical to drywall, drywall to substantial completion—drives both cash conversion and overhead absorption. Builders who can reliably hit 9 to 11 months on a custom home outperform peers who slip to 14 or 15 months on indistinguishable work.
Backlog dollars and months-of-work-in-hand at any point in time tells you whether your sales pipeline is keeping pace with your production capacity. A healthy custom builder typically wants 6 to 12 months of backlog at any given moment.
Warranty claim rate and average claim cost, tracked per home, are leading indicators of whether subcontractor quality and supervision practices are working. A builder with rising warranty incidents per home is heading toward a margin problem even if current jobs look profitable on paper.
Keep Your Construction Books Honest from the First Foundation
Custom home building rewards builders who treat their books as a live operational instrument, not a year-end compliance burden. The bookkeeping system you build—job cost categories, change order discipline, retainage tracking, warranty reserves, and tax method election—will determine whether your business compounds margin year over year or grinds down through hidden leaks.
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