If you're an employee entrusted with the company card, don't assume that the rules are the same as they are on your personal plastic.

Whether you're carrying a corporate charge card (which comes with an annual or monthly fee, does not accrue interest, and is paid in full monthly) or a company credit card (same as the ho-hum plastic -- including credit limits and interest rates -- all of us use), it pays to review the rules, particularly those that are company-specific. A few pointers:

1. Be prepared to let it all hang out
If you've had trouble with the plastic police in the past, and your company card is a standard credit card, the boss (or at least your finance department) will find out. Each person given access is subject to a credit check. Here are some tips on how to boost your credit score quickly, before you raise any managerial eyebrows.

2. Don't assume you can keep points or other perks
Many company credit cards come with perks that should sound familiar: miles, rebates, teaser rates, free balance transfers. Consult your employee handbook or your boss to see whether you are allowed to keep the spoils of your spending. If not, and if you are a diligent, on-time, paid-in-full kind of person, consider putting work purchases on your own personal card to earn extra points or cash back.

3. Make sure you get reimbursed
It doesn't take much to generate a mountain of receipts. Keep close tabs on your spending, especially if you're using your own credit card or cash for business-related expenses. (You want to get paid back, right?) If you get a generic receipt from a street vendor or corner deli, write on the receipt exactly what you purchased. Better yet, keep work-related expense records separate from your personal receipts. This is as simple as using an envelope for business receipts, and putting personal ones in your wallet. Finally, make sure you're timely in submitting your expenses for reimbursement. It's no fun footing the bill just because you missed the cutoff date for submissions.

4. Watch your wallet
Not all company credit card abuses are the fault of an unscrupulous employee. Unintentional abuse is easy. After all, it's just another piece of plastic in the wallet, and when you're fumbling for your card at the grocery store, mistakes can occur. As soon as you spot accidental personal charges on company plastic, tell your boss (and hand over a check for the personal purchases you put on the card).

5. Do the crime? Better pay on time
When it comes to company credit cards, abuses are legendary. Employees who put unauthorized charges on the company card may find themselves facing job loss, and worse. If you can't pay the tab, your company can treat the purchases as extra wages, and you will be taxed on them.

Bonus rule: Pay for the Waverunner personal watercraft with your own credit card
It may sound obvious, but apparently it's a rule that needs repeating, given that a bold Georgia Tech employee actually bought a Waverunner personal watercraft with her boss's dough. Last year, she was sentenced to 32 months in prison for racking up $316,000 in extravagant personal purchases -- including the watercraft, a $1,900 frozen drink system, power tools, and the requisite electronics and clothing items that abusers typically put on plastic.

Dayana Yochim always pays cash for her personal watercraft purchases. The Fool has a disclosure policy.