Every dollar that comes in and every dollar that goes out needs documentation. That is the baseline. But contractors have additional record-keeping requirements beyond what a typical small business deals with, and the ones who stay on top of it save real money at tax time and avoid problems with the IRS.

Start with income records. Keep copies of every invoice you send, every contract you sign, and every payment you receive. If a customer pays you in cash, write a receipt and keep a copy. Deposit slips, bank statements, and payment processor reports all support your reported income. The IRS pays close attention to cash-heavy businesses, and contractors fall squarely in that category.

Expense receipts are where most contractors fall short. Every material purchase, tool, supply run, fuel fill-up, and equipment rental needs a receipt. A bank or credit card statement alone is not enough. The IRS wants to see what was purchased, not just that money was spent. Get in the habit of photographing receipts the day you get them because thermal paper fades fast.

Job-related documents deserve their own filing system. Estimates, signed contracts, change orders, permits, inspection reports, and lien waivers should all be tied to specific projects. These protect you in disputes and give you real cost data for future bids. If you ever need to prove what was agreed to on a project, the paper trail is everything.

Subcontractor records are critical. Collect a W-9 from every sub before you pay them. Keep copies of their contracts, invoices, and proof of insurance. At year end you need to issue 1099s to any sub you paid $600 or more, and you can not do that without W-9s on file. Missing 1099s can trigger penalties and unwanted IRS attention.

Payroll records need to be kept for at least four years. That includes timesheets, pay stubs, W-4 forms, payroll tax filings, and workers’ comp documentation. California has strict labor laws and the penalties for incomplete payroll records are steep. If you have crews in the field, tracking hours accurately by job protects you on multiple fronts.

Vehicle and equipment logs matter more than most contractors realize. If you use a truck for both personal and business purposes, you need a mileage log to claim the deduction. Same with equipment. The IRS can disallow vehicle deductions entirely if you do not have a log showing business use percentage. This is one of the most commonly audited deductions for construction and contracting businesses.

Bank and credit card statements should be saved even though they are not sufficient proof on their own. They help reconcile your books and provide a secondary record if a receipt goes missing. Use a dedicated business account so personal and business transactions do not mix.

For retention periods, the general rule is three years from the date you file your tax return. But keep payroll records for four years, and keep anything related to property, equipment, or assets for as long as you own them plus three years after you sell or dispose of them. If you ever underreport income by more than 25%, the IRS has six years to audit you, so longer retention is safer.

The practical reality is that most contractors we work with through our contractor bookkeeping services did not have systems for any of this when they started. They had shoeboxes of receipts, missing sub paperwork, and no job-level tracking. Getting a system in place does not have to be complicated. A simple folder structure by month and by job, combined with a habit of capturing receipts digitally, handles 90% of what you need. The important thing is consistency. Records you keep sometimes are almost as useless as records you never keep.