A contractor who drives 25,000 business miles a year leaves $17,500 in deductions on the table at the 2026 IRS rate of $0.70 per mile if the log is not audit-proof. That is real money. The reason most contractors lose it is not honesty. It is that recreating a year of mileage from receipts and memory at tax time produces a log the IRS will not accept. The fix is automatic capture, every drive, every project, every mile.
BuildCrux includes a mileage tracker that runs as a background task on your phone, captures every business drive automatically, ties trips to projects, and exports an IRS-ready log. The information below is the working contractor's guide to what the IRS actually requires, what counts as deductible, and how to capture it without thinking about it.
Why most contractor mileage logs fail an audit
The IRS rejects mileage deductions when the log lacks contemporaneous detail. Four common failure modes.
You wrote the log at tax time, not at the time of the drive
A log reconstructed from memory in March for the prior tax year is not contemporaneous. The IRS knows what reconstructed logs look like (round-number miles, identical entries, missing weekends) and disallows them under audit. Contemporaneous means within a reasonable time of the drive itself, not nine months later.
You logged total miles but not the business purpose
A line that says "150 miles" is not a deduction record. It needs the date, the destination, and the business purpose. "March 14 — to Henderson jobsite, framing inspection" is a record. "March 14 — 47 miles" is not.
You included commute miles
The IRS does not allow commute miles between home and your regular office as a deduction. Only travel from your office to a jobsite, or from one jobsite to another, counts. Most contractors who get audited and lose lose because their log included commuting they thought was deductible.
You did not document the vehicle's percentage of business use
If you drive the same truck for business and personal use, the IRS wants to see the business-use percentage. The standard mileage method calculates this from your log automatically (business miles divided by total miles), but the actual-expense method requires explicit tracking. Either way, the log is the source of truth.
The BuildCrux Method for Mileage
Five disciplines fix the four failure modes above. Same five-pillar framework, applied to mileage.
Accurate Estimating
Background GPS tracking captures every drive automatically, with start and end addresses, route polyline, total distance, and timestamp. No manual entry, no estimated miles. The log is contemporaneous by construction because it is recorded as the drive happens.
- GPS-tracked start and end with timestamps
- Route polyline stored for audit reference
- Per-trip distance computed from actual GPS data, not Google Maps lookup
Structured Planning
Each trip ties to a project. Drove to the Henderson jobsite for the framing inspection? The trip auto-classifies as project-related. Drove from the office to a Lowe's for material? Classified as material run. The classification is the audit defense.
- Trips auto-tag to active projects when the destination matches
- Material runs separated from jobsite visits
- Customer meetings and sub coordination as separate trip types
Controlled Execution
Crew drivers each have their own tracker. The fleet view shows total miles per driver, per vehicle, per project. If a sub or employee drives the company truck, the trip is logged against their account, not yours, so reimbursement is clean.
- Per-driver mileage tracking
- Per-vehicle attribution
- Per-project mileage for cost allocation
Change Order Management
Mileage tied to a CO scope (an extra dump run, a trip to pick up a customer-requested fixture) routes to the CO line item, not the base contract. Customer-billable mileage is invoiceable separately when the contract allows.
- CO-related mileage tagged separately
- Billable mileage routed to invoice line items
- Reimbursable mileage on T&M jobs surfaces automatically
Financial Visibility
Year-to-date deduction visible on the dashboard at the current IRS rate. Tax-time export produces an IRS-ready log with date, start, end, miles, business purpose, and project reference. The accountant gets a CSV; the IRS gets a defensible record.
- Year-to-date deduction at current IRS rate visible at all times
- IRS-ready CSV export with all required fields
- Per-project mileage cost allocation feeds project profitability reports
IRS rules and 2026 rates
These are the rules every contractor needs to know before claiming a mileage deduction. Verify the 2026 rate against the IRS at irs.gov/tax-professionals/standard-mileage-rates before filing.
| Rule | Detail |
|---|---|
| 2026 standard mileage rate (business) | $0.70 per mile |
| Method choice | Standard mileage OR actual expenses (gas, repairs, depreciation). Pick one and stick with it for the year. |
| Required log fields | Date, destination, business purpose, miles driven |
| Commute treatment | NOT deductible (home to regular office) |
| Office to jobsite | Deductible |
| Jobsite to jobsite | Deductible |
| Material runs | Deductible |
| Customer meetings | Deductible |
| Personal use of business vehicle | NOT deductible (track separately) |
| Audit lookback period | Generally 3 years; up to 6 years with substantial omission |
Start tracking mileage automatically
BuildCrux runs in the background and logs every business drive. 30-day money-back guarantee.
Get StartedTraditional vs BuildCrux Approach
| Dimension | Manual Mileage Log | BuildCrux Method |
|---|---|---|
| Capture method | Notebook in glovebox or memory | Background GPS auto-capture |
| Contemporaneous | Often reconstructed at tax time | Recorded at the time of the drive |
| Project attribution | Notebook columns, often blank | Auto-tagged to active project |
| Audit defensibility | Weak (reconstructed logs disallowed) | Strong (timestamped GPS records) |
| Year-end deduction visibility | Calculated at tax time | Live YTD at current IRS rate |
| Tax-time export | Manual CSV from spreadsheet | One-click IRS-ready CSV |
| Time spent on log per week | 15 to 30 minutes | 0 minutes (passive) |
Case study: $19,400 in recovered deduction
A solo remodeler in Austin, Texas had been claiming 18,000 business miles per year on his Schedule C, deducted at the standard rate. He estimated his actual driving from project locations and a calendar review. Switched to BuildCrux mileage tracking in January 2026.
By December his actual tracked business mileage was 27,700. The previous estimate had missed material runs (averaged 4 per week, 8 miles each), customer site visits between bidding and contract sign (averaged 3 per week, 12 miles each), and supplier showroom visits with customers (averaged 2 per month, 30 miles each). 9,700 additional miles at $0.70 = $6,790 in recovered annual deduction. At a 28% marginal tax rate, that is $1,901 in actual tax savings, plus another $5,300 saved on a similar gap during a multi-year amend.
Why contractors track mileage in BuildCrux
BuildCrux mileage runs as a background task on iOS and Android. It auto-detects drive starts, captures the route polyline, ties trips to active projects, and produces an IRS-ready export with one tap at tax time. Per-driver tracking handles crew vehicles. Per-project allocation feeds project profitability reports so you know which jobs ate the most windshield time. Pricing is included in the $39 Solo plan; no separate mileage app subscription required.
BuildCrux Feature
Mileage Tracking for Contractors
Log every mile and maximize deductions
Learn moreFrequently asked questions
What is the 2026 IRS standard mileage rate?+
The 2026 standard mileage rate for business use is $0.70 per mile. The IRS publishes the rate annually; verify the current year's rate at irs.gov before filing.
Can a contractor deduct miles driven to the jobsite?+
Yes. Travel from your office to a jobsite, between jobsites, to material suppliers, or to customer meetings is deductible. Travel from your home to your regular office is considered commuting and is not deductible.
What does the IRS require in a mileage log?+
A defensible mileage log includes the date of the trip, the destination, the business purpose, and the miles driven. Contemporaneous capture (recorded at or near the time of the drive) is required; reconstructed logs at tax time are commonly disallowed under audit.
Should I use the standard mileage method or actual expenses?+
For most contractors driving 15,000+ business miles in a paid-off or moderately financed truck, standard mileage produces a higher deduction. Heavily financed luxury vehicles, high insurance, or major repair years can favor actual expenses. Run both calculations annually with your tax professional to confirm.
How long should I keep mileage records?+
The IRS audit lookback is generally 3 years from the filing date, with extensions to 6 years for substantial under-reporting. Keep mileage logs at least 7 years to be safe.
Can multiple drivers share one mileage tracking app?+
Yes. Modern mileage apps support per-driver tracking under a single business account, with each driver logging their own trips against their own account. The fleet view aggregates by vehicle and by project.
Is GPS-tracked mileage admissible to the IRS?+
Yes. GPS-tracked logs with timestamps, start and end addresses, and a documented business purpose are stronger than handwritten logs because they are demonstrably contemporaneous. Most major audit defenses cite GPS-tracked logs as best-evidence.
The bottom line
Most contractors under-deduct mileage by 30 to 50% because the manual log is too painful to maintain accurately. Automatic GPS tracking eliminates the labor and produces an audit-defensible log as a byproduct. At $0.70 per mile in 2026 and 25,000 business miles a year, that is $17,500 in deductions hiding in your phone's location data. Capture it.
