Why construction bookkeeping breaks standard accounting software

Most small-business accounting software is built on a simple premise: you sell something, you invoice for it, the customer pays, and the transaction closes. Construction violates that premise at nearly every step. A contractor may work for eight months before the job is finished, bill monthly against a schedule of values that an architect has to certify, have a slice of every payment legally withheld until the work is accepted, and then report the income to the IRS on a schedule that has nothing to do with when the cash actually arrived. Three mechanics drive that divergence — job costing, retainage and progress billing — and each one breaks a different default assumption.

The tax code does not wait for the job to finish

The starting point is federal. Under 26 U.S. Code § 460(a), for any long-term contract "the taxable income from such contract shall be determined under the percentage of completion method (as modified by subsection (b))." Section 460(f)(1) defines a long-term contract broadly enough to catch ordinary construction work: "any contract for the manufacture, building, installation, or construction of property if such contract is not completed within the taxable year in which such contract is entered into." A job started in October and finished in March is, for these purposes, a long-term contract.

Percentage-of-completion means income is recognized as costs are incurred, based on an estimate of total costs — which is why a contractor's books have to track costs against each job, not just against the company. That is job costing, and it is not a reporting preference. It is the input the tax method runs on.

There is an escape hatch, and it is the most consequential number in the small-contractor world. The IRS Instructions for Form 8697 (Rev. 12-2025) state that the look-back method does not apply to "[a]ny other construction contract entered into by a taxpayer (a) who estimates the contract will be completed within 2 years from the date the contract begins, and (b) whose average annual gross receipts for the 3 tax years preceding the tax year in which the contract is entered into do not exceed $31 million (adjusted for inflation) for contracts entered into in tax years beginning in 2025."

That threshold moves with inflation, and published guidance is not uniform on the current figure. The Form 8697 instructions themselves flag this, noting the amount "may be adjusted for inflation" and that the instructions "may not be revised to reflect this amount." The primary source resolves it: Revenue Procedure 2025-32 states that "[f]or taxable years beginning in 2026, a corporation or partnership meets the gross receipts test of § 448(c) for any taxable year if the average annual gross receipts of such entity for the 3-taxable-year period ending with the taxable year which precedes such taxable year does not exceed $32,000,000." Secondary commentary circulating in 2026 still cites the $31 million figure — that is the 2025 number, not the 2026 one.

Look-back interest: the bill for guessing wrong

Percentage-of-completion runs on estimates, and the IRS charges for estimates that turn out to be wrong. Form 8697 exists, per its instructions, "to figure the interest due or to be refunded under the look-back method of section 460(b)(2) on certain long-term contracts." When a contract closes, income is recomputed using actual costs, and interest runs on the resulting under- or overpayment for the intervening years.

Two carve-outs matter. The small contract exception removes contracts completed within two years of the start date where the gross contract price does not exceed "the smaller of: $1 million, or 1% of the taxpayer's average annual gross receipts for the 3 tax years before the tax year of contract completion." And a de minimis election is available where, for each prior contract year, "the cumulative taxable income (or loss) actually reported under the contract is within 10% of the cumulative look-back income (or loss)." The instructions also note that for long-term contracts entered into after July 4, 2025, the two-year window in the small contract exception becomes three years, and the look-back method no longer applies to regular taxable income from residential contracts.

Progress billing has its own document set

Contractors do not invoice the way a retailer does. The industry runs on AIA Document G702, Application and Certificate for Payment, paired with G703, the Continuation Sheet. Per AIA Contract Documents, G703 "breaks the contract sum into portions of the work in accordance with a schedule of values prepared by the contractor as required by the general conditions." The G702 shows "the contract sum to date, including the total dollar amount of the work completed and stored to-date, the amount of retainage (if any), the total of previous payments, a summary of change orders, and the amount of current payment requested."

The structural difference from ordinary invoicing is certification: the architect certifies that payment is due. A pay application is a claim assessed by a third party, not a demand issued unilaterally. Generic invoicing modules have no concept of a schedule of values, no line-item percent-complete, and no certification step.

Retainage is a moving legal target

Retainage — money earned but withheld until acceptance — is where a contractor's revenue and cash position permanently diverge, and where the rules differ by state and by project type. The trend is toward tighter caps. New York amended sections 756-a and 756-c of the General Business Law effective November 17, 2023, limiting retainage "to no more than 5%" on private construction contracts where the aggregate project cost "equals or exceeds one hundred fifty thousand dollars," and permitting contractors to "submit a final invoice to the owner for payment in full upon reaching substantial completion." California's Senate Bill 61 took effect January 1, 2026; per the law firm O'Melveny, "[t]he maximum retention held by owners, direct contractors, or subcontractors cannot exceed 5% of a given progress payment" and "[t]he overall amount held in retention cannot exceed 5% of the total contract price." O'Melveny notes the cap "cannot be waived, even by the parties' agreement," and that it does not limit retention for residential-only, non-mixed-use projects of four stories or fewer.

Not every state has moved. Illinois, per industry summaries, allows 10% on private non-residential work until the contract is 50% complete, after which withholding must drop to 5%. Georgia capped public-project retainage at 5% for contracts executed on or after July 1, 2022. A contractor working across state lines is applying different arithmetic to the same accounting line.

What this means for the books

The practical consequence is that a construction ledger has to carry information a general ledger was never designed to hold: cost by job and cost code, percent complete by line of the schedule of values, retainage receivable tracked separately from ordinary receivables, and an estimate of total job cost that is revised as the job runs. Under- and over-billing — the gap between what has been earned and what has been invoiced — is a real balance-sheet item that generic software will not surface at all.

Contractors who conclude they need construction-specific help usually start by comparing providers. Directory and matching services exist in this space; one is Contractor Ledger Pro, which by its own disclosure is a lead generation service that connects contractors with bookkeeping professionals rather than performing the work itself. That distinction is worth confirming with any service before engaging, because a matching intermediary and a bookkeeping firm carry different accountability for the numbers on your return.

Verification

Tax provisions verified against 26 U.S. Code § 460, IRS Instructions for Form 8697 (Rev. 12-2025) and IRS Revenue Procedure 2025-32, retrieved July 2026. Billing document conventions verified against AIA Contract Documents guidance on G702 and G703. Retainage limits verified against published law-firm analyses of New York General Business Law sections 756-a and 756-c and California SB 61. Inflation-adjusted thresholds and state retainage caps change; confirm current figures at irs.gov and with counsel in the relevant state before relying on them.