Honestly? There's no single answer here. It totally depends on what kind of log book we're talking about and why you're keeping it. For tax stuff and business expenses, the rule of thumb is hang onto it for three to seven years after you file your return. But if you're a truck driver tracking hours of service? That's usually just six months. Let me walk you through the specifics, so you don't accidentally trash something important and end up in hot water. For commercial drivers in the U.S., the FMCSA says you gotta keep your record of duty status - that's your log book - for six months from the date of the record itself. Paper logs, electronic logging devices, doesn't matter. The company you drive for is responsible for holding onto these. And if an inspector asks to see them? You better have 'em ready. Mess that up and you're looking at fines that'll ruin your day, maybe even an out-of-service order. If you're tracking mileage or vehicle costs for your taxes, the IRS wants you to keep supporting documents as long as they matter for your return. Standard rule? Three years from when you filed, or two years from when you paid the tax - whatever comes later. But here's the kicker: if you underreported your income by more than 25%, they can come after you for six years. And if there's fraud or you never filed? Yeah, that's indefinite. Play it safe and keep business logs for at least seven years. Seriously. Depends on who's asking. For truckers? Ditching your log book before six months is up means FMCSA fines, man. Hundreds, maybe thousands per violation. For taxes? Toss that mileage log too early and you lose your backup during an audit. The IRS will just disallow your deductions, hit you with penalties and interest. Ouch. And if you're in a lawsuit or insurance claim? Destroying a log book prematurely could blow up your whole case. Not worth it. Yeah, digital's fine. Retention periods stay the same. FMCSA's cool with electronic records, and the IRS accepts digital docs as long as they're legible and accurate. The big thing? You gotta be able to reproduce it in a readable format if someone asks. ELDs automatically back stuff up. For mileage logs, apps make tracking way easier. But the storage method doesn't change the legal timeframes. Just don't think you can delete things early because it's on your phone. Try to reconstruct it as best you can from other sources - GPS data, fuel receipts, appointment calendars. For driver's logs, you might need to file a correction with your employer. If you can't produce it during an inspection or audit, you're looking at penalties. So get proactive about rebuilding those records. For driver's logs, count six months from the date of the record. For tax logs, start from when you filed your return (or the due date, whichever's later). To be safe, always count from the later event. Like, if you filed April 15, 2024, keep that 2023 mileage log until at least April 15, 2027. Absolutely. If your log book's relevant to a lawsuit, insurance claim, or investigation, you keep it until that's fully resolved - even if the standard period's passed. Destroying records under a legal hold? That can get you severe sanctions, adverse inference rulings, spoliation claims. Don't mess with that. Talk to legal counsel before trashing anything tied to litigation. Yes, if you're claiming business deductions for mileage or expenses on a personal car. Same retention rules as any business tax record. No log book? The IRS might just disallow your deduction. So keep detailed records for at least three to seven years. Better safe than sorry.How long do I need to keep a log book for
What is the standard retention period for a driver's log book?
How long should I keep a log book for business expenses and taxes?
Data Table: Log Book Retention Periods
Type of Log Book
Regulatory Body
Recommended Retention Period
Key Notes
Driver's Log Book (HOS)
FMCSA (USA)
6 months
Must be kept on file by the carrier; includes ELD data.
Business Mileage/Expense Log
IRS (USA)
3-7 years
Keep for 3 years after filing; 7 years if underreported income.
Medical/Health Log
Varies (e.g., HIPAA)
6-10 years
Check specific state and federal regulations.
Construction/Project Log
Varies (OSHA, contracts)
5 years (OSHA)
Longer if related to ongoing litigation or warranty claims.
What are the consequences of not keeping a log book long enough?
Can I keep a log book digitally, and does that change the retention period?
Checklist: How to Manage Your Log Book Retention
Frequently Asked Questions (FAQ)
What happens if I lose my log book before the retention period ends?
Does the retention period start from the date of the log entry or the date of filing?
Are there different rules for log books used in legal proceedings?
Do I need to keep a log book for a personal vehicle used for business?
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