Contractor Bookkeeping Guide

The financial side of contracting is nothing like a typical small business. You are not tracking one revenue stream and a handful of recurring expenses. You are managing multiple active projects, each with its own budget, timeline, crew, subcontractors and materials, all moving at once.

Miss a cost on one job and a 15% profit margin becomes 3%. Lose track of a subcontractor’s payments and you scramble to file 1099s in January. Bill a milestone late and cash flow takes a hit that ripples through every other project.

This guide covers job-level bookkeeping for contractors: job costing, subcontractor tracking, progress billing and cash flow planning.

Why Generic Bookkeeping Falls Short for Contractors

Most bookkeeping advice assumes a business that sells products or bills hourly. Contractors operate differently:

• Every dollar ties to a specific job. A lumber purchase belongs to the Thompson kitchen remodel, not to general overhead. Without job-level cost records you cannot see profitability.
• Revenue recognition is complicated. You do not earn revenue when you send an invoice. You earn it as work progresses. Percentage-of-completion accounting requires tracking estimated against actual completion on each project.
• You work with many subcontractors. Each needs payment tracking, W-9 collection and 1099-NEC filing. A subcontractor is more than another vendor.
• Cash does not flow in a straight line. Progress billing schedules, retention holdbacks, seasonal slowdowns and clients who pay 60 days late make your cash position swing from month to month.

Job Costing: The Foundation of Contractor Profitability

Job costing is the most important financial practice for a contractor. It tells you whether a project made money while you can still make adjustments, not after the job is closed.

What Goes Into a Job Cost

Every project has five cost categories:

• Direct labor: wages, payroll taxes and benefits for workers assigned to the job
• Materials: lumber, concrete, electrical, plumbing, fixtures and other supplies bought for the project
• Equipment: rental costs for excavators, lifts and compressors, or depreciation on owned equipment used on the job
• Subcontractors: payments to specialty trades such as electrical, plumbing, HVAC and roofing
• Overhead allocation: your share of office rent, insurance, vehicle costs and administrative salaries, spread across active jobs

Sample Job Cost Breakdown

The table below uses illustrative figures for a $185,000 residential remodel.

Cost Category	Budgeted	Actual	Variance
Direct Labor	$42,000	$44,800	-$2,800
Materials	$51,000	$48,200	+$2,800
Equipment Rental	$8,500	$9,100	-$600
Subcontractors	$38,000	$38,000	$0
Overhead (15%)	$20,925	$21,015	-$90
Total Cost	$160,425	$161,115	-$690
Contract Price	$185,000	$185,000
Gross Profit	$24,575	$23,885	-$690
Profit Margin	13.3%	12.9%

In this example a labor overrun ate into profit, and a materials saving offset most of it. Without job costing you would see only the final number, with no idea why the margin came in thin or how to bid more accurately next time.

A Job Costing Routine

1. Create a job: enter the contract value, estimated costs by category and expected timeline
2. Assign expenses as they happen: tag every receipt, invoice and payroll entry to a job
3. Review budget against actual: check percentage complete and projected final margin for every active project
4. Close out and analyze: produce a final cost report and keep it, so future estimates improve

New to setting up your books? The guide on how to do bookkeeping for a small business covers the fundamentals.

Subcontractor 1099-NEC Management

Payments to subcontractors above the IRS reporting threshold require a 1099-NEC. The threshold is $2,000 for payments made in 2026 and $600 for payments made before 2026. The rule applies to electricians, plumbers, drywall crews, painters, concrete finishers and every other sub you pay as a business.

Penalties for filing late or incorrectly exist and increase with how late the form arrives. Check the current IRS schedule when planning your filing timeline.

Tracking Sub Payments

• Log every payment: keep a running total per subcontractor as you pay invoices
• Watch the threshold: note when a sub approaches the reporting threshold
• Collect W-9s early: name, address, taxpayer ID and entity type are easier to gather before the first payment than in January
• Prepare forms at year-end: with a complete log, the forms are a matter of copying totals, not reconstructing a year from bank statements

Progress Billing and Percentage-of-Completion

Unlike businesses that invoice monthly for services rendered, contractors typically bill by project milestones or percentage of work completed. This is standard in commercial construction and common in larger residential work.

How Percentage-of-Completion Works

The formula is straightforward:

Billable amount = (Costs incurred to date / Total estimated costs) x Contract price

For example, on a $185,000 contract with $160,425 in estimated total costs:

• After spending $48,125 (30% of estimated costs), you can bill 30% x $185,000 = $55,500
• After spending $80,210 (50%), you can bill 50% x $185,000 = $92,500
• At 50%, cumulative billing of $92,500 minus $55,500 already billed = $37,000 invoice

Update costs incurred as they arrive. Then the billable amount is ready when it is time to send a draw request or progress invoice.

Milestone Billing

Some contracts specify fixed billing points such as foundation complete, framing complete and rough-in complete. Record each milestone per project and invoice when it is reached.

Either way, keep a running comparison of billed against unbilled revenue so you know how much you have earned but not yet invoiced.

Change Orders: Protecting Your Margin

Change orders are a fact of life in contracting. The client wants to upgrade the countertops. The architect revises the plans. An unexpected site condition adds two weeks of work.

Each change order affects profitability. Untracked, your final margin will be a surprise, usually an unpleasant one.

Log each change order with:

• The original scope and budget
• The revised scope and additional cost
• Whether the client approved the change
• The impact on the project timeline

Every approved change order updates the job cost record. A job bid at 15% margin with $12,000 of approved change orders needs a new contract value, new estimated costs and a revised margin.

Seasonal Cash Flow: Planning for the Slow Months

For contractors in northern states, winter can mean two to four months of reduced or zero revenue. Even in milder climates, seasonal patterns affect cash flow.

The slow season itself is not the problem. Failing to plan for it is. Fixed costs continue whether you are pouring concrete or not: insurance premiums, truck payments, office rent and loan payments.

A cash flow forecast built from your historical revenue and current project pipeline can look three to six months ahead. Include:

• Active project billing schedules
• Retention holdbacks and expected release dates
• Seasonal revenue decline based on your history
• Fixed monthly obligations
• Expected subcontractor and supplier payments

A forecast that shows a shortfall three months out leaves time to act: line up a credit line, accelerate billing on a current project or delay an equipment purchase.

Retention Tracking: Money You Have Earned but Cannot Spend

Retention (or retainage) is the portion of each progress payment, typically 5% to 10%, that the general contractor or owner withholds until the project is substantially complete. On a $185,000 job with 10% retention, $18,500 sits in someone else’s account until you finish the punch list.

Across several active projects, retention can represent a large amount of earned revenue that has not reached your bank account. Track it separately from standard accounts receivable, with:

• Total retention outstanding across all jobs
• Retention amount per project
• Expected release dates, based on completion timelines or warranty periods
• Aging of retention receivables

This visibility matters for cash flow planning and for conversations with your bank about working capital.

Quarterly Estimated Taxes for Contractors

Contractors are usually self-employed or own pass-through entities such as LLCs and S-corps, so income tax is not withheld from revenue. You are responsible for quarterly estimated tax payments to the IRS and, in most states, to your state tax authority.

Contractor income is lumpy. Heavy collections in two quarters followed by very little in the next two can mean big overpayments in slow quarters or underpayments in peak season. Base each estimate on income received and deductible expenses recorded, not on annual projections alone.

Getting Started With Contractor Bookkeeping

A basic contractor setup takes an afternoon:

1. Separate business bank accounts and credit cards from personal ones
2. Set up your active jobs with contract values, estimated costs and billing milestones
3. List your subcontractors with any W-9s you hold on file
4. Set categories for vendors, material suppliers and expense types
5. Note fixed monthly costs and seasonal patterns so a forecast is possible from day one

The monthly bookkeeping checklist gives you a routine to follow each month.