Why Your Utility Bill Isn't Enough
Your electric bill proves you bought electricity — it doesn't prove how much went into your car, let alone which charges were for business. The IRS standard for vehicle expenses is adequate, contemporaneous records: created at or near the time of the expense, not reconstructed in April from memory. For EV charging deductions, that means a per-session log.
What a Defensible Charging Log Contains
| Field | Why the IRS cares |
|---|---|
| Date & time | Proves the record is contemporaneous and matches your business calendar |
| kWh delivered | The quantity of "fuel" — the basis of the whole deduction |
| Cost | Your utility rate at that time, or the public charger's actual price |
| Location | Home vs. workplace vs. public — different rates, different treatment |
| Vehicle | Deductions are per vehicle; multi-EV households need separation |
| Business-use % | Only the business share is deductible |
Three Ways to Keep the Log
1. Spreadsheet (free, fragile)
Works in theory. In practice, nobody records a 2 a.m. scheduled charge by hand, and gaps are exactly what makes an auditor discard a log. Reconstructed records look reconstructed.
2. Dedicated kWh Submeter (accurate, expensive)
An electrician-installed submeter on the charger circuit typically costs $250–600 all-in. It measures precisely but still doesn't produce session records, business-use splits, or reports — you're back to the spreadsheet for those.
3. Automatic Capture From Your Wallbox (accurate, zero effort)
Your wallbox already measures every session to the watt-hour. An app that reads it — like ChargeDoc — gets meter-grade data with none of the manual work, and formats it the way a tax preparer needs it.
How ChargeDoc Keeps the Log for You
- Connect once: Wallbox Pulsar (cloud), go-e Charger, or Tesla Wall Connector Gen 3 (local WiFi).
- Every charge becomes a record — date, kWh, duration, cost at your configured rate, location, and vehicle. Charges that happen while the app is closed are captured afterwards.
- Public sessions are added in seconds with their actual price and tagged by location.
- Audit trail built in: ChargeDoc keeps an internal audit log, and your data can be backed up to a single encrypted file.
- Export: IRS Business Use Report (Schedule C basis), universal PDF summary, or employer reimbursement PDF — per-session details plus monthly and yearly totals.
How Long to Keep the Records
The IRS can generally look back three years, and up to six in some cases. Because ChargeDoc stores everything locally on your device (with encrypted backup), your history doesn't expire when a charger app decides to only show the last 12 months.
Disclaimer: ChargeDoc reports are informational only and not tax advice. Consult a CPA or tax advisor before filing.