11 of my coworkers shared their worst money mistakes - or the gaffes they almost made

Not checking with my insurance ahead of time to make sure a new doctor is within my coverage! It seemed like such a pain, but most providers have online systems, chat programs, or helpful customer service reps that will help verify the decision.

After a few several hundred dollar charges, I learned my lesson and always double check.

— Christina Sterbenz, weekend editor

For spring break of my sophomore year in college, a few friends and I rented a house near the beach in San Juan, Puerto Rico. It wasn't the nicest part of the city, and we made ourselves known by hanging out on the balcony and by our Puerto Rican friends' expensive cars in the driveway.

We spent one night at a club and came back right before dawn. When we finally woke up the next day, we each noticed some of our things seemed to be misplaced, or even missing. Eventually we came to the conclusion that someone had broken into the house via the balcony's weak door and robbed thousands of dollars worth of our stuff.

I was the worst hit: They stole my laptop, a MacBook Pro worth about a couple grand. They also took my two favorite pairs of rare Nikes and an expensive, new bottle of cologne. For some reason they even stole my retainer!

Lesson: There's no need to travel with your valuables, and there's no need to pack so heavy! If you have to bring something valuable, for a special occasion, keep it on your person or lock it up. I was a dumb 19-year-old who didn't yet know the value of money or how to prepare for a vacation, but this was a good, if unfortunate, step forward!

— Anonymous

I got a cat in May. She has a habit of getting under your feet while you walk around in the apartment. I was late for work early in August and was running down my hallway to get something from my room and I kicked her and actually broke her arm at the elbow joint.

Thus began the nightmare that was my entire month of August. I went to the emergency vet at least six times, figuring out how to fix my cat's broken leg. By the time it was all said and done, I had spent over $2,000 on fixing my cat. I had to pay hundreds for x-rays, splints, cast materials, check ups, physical therapy, etc. And probably $200 on Ubers alone just getting her to and from the emergency vet.

My most expensive mistake was not looking where I was going and kicking my cat.

— Ben Nigh, associate video producer, INSIDER

I worked for a startup that was actually lucky enough to IPO, and I had some stock options that were in the money. When I left, I exercised my options, but instead of selling all the shares, I took some bad advice from a neighbor who had once sold a company and held on to half of them.

The market later changed and the value of those shares dropped by something like 80%. So first, I had to pay a $15,000 tax bill on the value of the options at the time I exercised — although I got it back from the IRS over the next few years.

Then, when I finally sold the remaining shares, they were worth about $50,000 less than when I exercised them.

Lesson: Sell when you exercise! The regret you may have if the stock goes up is blunted by the cash you'll have in your pocket, and you deserve that compensation for giving up the salary you would've made working for a more established company. Hold on to 10% if you really want to be sure you don't miss out on a crazy upside ride. But sell most of it.

— Anonymous

I once lost $1,400 on a security deposit for an apartment because I didn't check it carefully enough before putting the money down. It was a place in Williamsburg, a couple of colleagues lived in the building and liked it, so I wasn't as thorough as I should have been when I went and looked at the apartment.

The broker was warning us that other people were very interested in the unit, so my roommate and I wrote checks for a security deposit after one quick walk-through and a couple of basic questions.

I went back to the apartment to do a more thorough walk-through before I signed the lease and paid the first month's rent, and found no fewer than a dozen dead cockroaches in the kitchen cabinets. I decided that losing the money was worth it to avoid the stress of dealing with a full-scale infestation in a new apartment.

— Pam Engel, senior politics reporter

A few years ago, we almost got scammed out of $3,000 and had our sailboat stolen. We had put the boat up for sale and someone had contacted us wanting to buy it. The person lived overseas and wanted us to ship the boat to them. He sent a cashiers check that included payment to us, plus the extra amount to cover shipping. He said he'd schedule the shipper to come by the next day, after the cashier's check cleared. He needed us to transfer the extra funds into another, local US account, so he could pay the local shipper, was the story.

Everything about this sounded like a scam. We knew it at the time. But my husband had the cashier's check in hand and deposited it. He called the bank the next day and sure enough, the bank confirmed the money was there — it was cleared.

On the day the shipper is supposed to come, my husband goes to transfer the money and the money is gone.

As you probably already suspected, the check was fake. It turns out that banks will release funds to you on a cashier's check right away, and if it gets returned as a fraud, they pull the funds back out. This can take several days or even longer, when you think the money is there but it's not. The bank wasn't liable for releasing funds to us on a bad cashier's check, either.

So if we had gone ahead with the transaction, the thieves would have gotten our money, $3,000, and potentially taken our boat, too.

We learned two things: You really can't trust a cashier's check, and obviously, if it sounds like a scam, just say no to the whole situation and walk away. But it's easier to get caught than you think it is.

— Anonymous

My wife and I had tried to get pregnant for more than a year on a top-of-the-line (i.e. no coinsurance) health plan, but our uncertain struggle and a steep increase in premiums for that plan tempted us toward the lower-cost 20% coinsurance plan.

Naturally, we got pregnant with our first child days after open enrollment ended. Accounting for premiums, deductions for a flexible spending account (to pay down our bills with tax-free money), and negotiating bills with our healthcare providers, we're paying roughly $2,000 more than we would have if we'd just stuck with the premium health plan.

Our baby is healthy and beautiful, but if we have another we're going to take this expensive lesson to heart.

— Anonymous

My husband and I recently bought a house. It was our first time going through the (chaotic and expensive!) process — and we were admittedly a bit naive about a few things. Luckily, we have our parents, who we'd consult and ask questions along the way.

Right before we went into contract, while we were still negotiating the price of the house and calculating all the associated costs, I had asked my broker about any other fees we were forgetting. She said, "My fees are about $11,600, so add that to your closing costs."

"That stinks — and it's an added cost we really can't afford," I thought.

I guess I hadn't really thought much about it, but it made sense at the time that we'd pay the realtor. I mean, we were using her services, after all. So, I didn't question it. I just figured there was nothing we could do about it — and we'd have to suck it up and pay.

(Quick piece of advice: Don't believe ANYTHING, ANYONE tells you when you're buying a home. Question and negotiate everything!!)

The next day, I casually mentioned this to my mom. "Absolutely NOT!" she said. "The buyer almost NEVER pays the broker fee. That's the seller's responsibility." I did a quick Google search, which confirmed she was right (moms are always right!).

I emailed the broker back and called them out on it. "Yes, normally you wouldn't pay," she admitted. "But the seller said since you're getting such a great deal on the house, they'd like you to pay it."

I told her that we were not willing to pay it. If that was a deal-breaker, so be it (but we secretly hoped it wasn't, since we were already so emotionally invested). A few minutes later, I got a response: "Okay, the seller will pay the broker fee." BAM! We paid the realtor not a penny.

As young home buyers who were new to the process, I think we were being taken advantage of. Had I not told my mom, we could have ended up paying close to $12,000 that we didn't have to pay. And I can't even imagine how I'd feel if I figured that out later!

— Anonymous

I failed to read the fine print on data usage when I bought internet access for an international flight. Even though I only checked my email a few times, apps must have been running in the background, because I ended up with a $500 bill at the end.

Fortunately, the company providing access was understanding and refunded my money.

— Ariel Schwartz, deputy editor, innovation

When I purchased a car back in the mid-'00s, I was looking to trade-in my old car, a Chevy Cavalier that was getting pretty old. I had started looking around for a used replacement car and had even found one that I liked, a Toyota Corolla. The dealership gave me a trade-in price for the Corolla — $1,000 — and I left to think about it.

A few days went by and suddenly a small part on my old car broke, one that would have cost twice as much as the car was worth to repair. When I called up the car dealership, they were still willing to take the trade-in, but for only $500, which was half the value they originally quoted me.

The car was getting so old that it was going to be sold for parts either way, but the dealership knew they had me in a hard place. And in the end I also lost any negotiating room I had on the new car, so I had to pay the sticker price of the new car.

What I learned in the end was to always get rid of a car when it's near the end, otherwise you'll end up losing money.

— Darren Weaver, senior video producer

I got an email from our HR department that my health insurance plan was going to be phased out of our company's offerings. If I didn't choose a new plan during open enrollment, I would be automatically reassigned to another one. I wasn't paying attention to the dates of open enrollment, for some reason assuming it wasn't for another month or so.

By sheer luck I happened to ask one of my colleagues when the period started ... on the last day ... at 4 p.m.! I was able to pick a comparable plan to my previous one, and it's a good thing I did — the default plan I would have been stuck with for the next year had an extremely high deductible.

— Anonymous