Look, filling out a log book isn't rocket science, but get it wrong and you're in for a world of pain come tax time. Whether it's for your car, your work hours, or some training thing, the basics are pretty much the same. A log book isn't just some notebook you scribble in—it's a legal document that needs to be accurate, readable, and done on time. Let me walk you through it using the most common one: a vehicle log book for business expenses. Every single entry needs certain bits of info to actually count. For a vehicle log, you're looking at the date, what the trip was for, your odometer readings at start and finish, and the total distance. Oh, and don't forget where you started and where you ended up. Sounds obvious, right? But you'd be surprised how many people skip the addresses. A proper entry lets you figure out what percentage of your driving is business-related, which is what the tax folks care about. Okay, let's make this real. Say you've got a company car and you're driving to see a client. Here's how the entries might look. See how the first two trips are business? The third one's personal. To get your business percentage, you add up all the business kilometers (160 here) and divide by total (180). That gives you 88.9%. Simple math, but it matters a lot. Commercial drivers have a different beast. It's called a driver's daily log or hours of service log, and yeah, it's a legal thing. You're tracking your duty status every 15 minutes. Seriously. You note driving hours, on-duty but not driving, off-duty, and sleeper berth time. Plus carrier name, office address, total miles. An example? Driver starts at 6 AM, drives till 10, takes a 30-minute break, then drives again from 10:30 to 2 PM. That kind of thing. People mess up all the time. Biggest one? Waiting till the end of the week to fill it in. Then you're guessing odometer readings, and that's just asking for trouble. Inconsistent abbreviations or handwriting that looks like chicken scratch—yeah, that's a problem. For tax purposes, not writing the specific business purpose is a killer. "Work" doesn't cut it. And here's one everyone forgets: logging personal trips. Skip those and your business percentage is way off, which auditors love to catch. Yeah, you do. Even if it's once a month, you need a log book to claim expenses. You've gotta track every trip for 12 continuous weeks to establish your business use percentage. Personal trips count too—don't skip them. Sure, digital ones are fine. Tax authorities accept apps that use GPS tracking—honestly, they're probably more accurate than paper. But the rules are the same: you still need to note the purpose of each trip and be ready to show it if you get audited. Don't panic. Just draw a single line through the error and write the correct info next to it. No white-out, no erasing. Initial the correction so it looks intentional. If you're making a lot of mistakes, that's a red flag. Usually three to seven years after the tax year. Depends where you live. Check your local rules. For commercial driver logs, it's shorter—maybe six months to a year. But better safe than sorry.How do you fill out a log book example
What are the essential parts of a log book entry?
Step-by-step example: Filling out a vehicle log book
Date
Purpose
Start Location
End Location
Start Odometer
End Odometer
Total km
15 Oct 2023
Client meeting - ABC Corp
Office HQ, 123 Main St
ABC Corp, 456 Oak Ave
45,200
45,280
80
15 Oct 2023
Return to office
ABC Corp, 456 Oak Ave
Office HQ, 123 Main St
45,280
45,360
80
16 Oct 2023
Personal errand (grocery)
Home, 789 Pine Ln
Home, 789 Pine Ln
45,400
45,420
20
How do you handle a log book for a driver's daily log?
What are the most common mistakes when filling out a log book?
Checklist for a perfect log book entry
Frequently asked questions
Do I need to keep a log book if I only use my car for business occasionally?
Can I use a digital log book instead of a paper one?
What happens if I make a mistake in my log book?
How long do I need to keep my log book records?
Short Summary
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