The 11 dumbest things to do with money in your 30s

Time is still very much on your side in your 30s — if you manage your money well, it can mean huge financial gains in the future.

That’s easier said than done. Plus, many of us tend to assume we’ll have more money in our 40s and have plenty of time to tune up our finances, which can lead to some poor money decisions.

Here are 11 of the worst, and how to combat them:

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Tapping into employee benefits could save you thousands of dollars each year.

1. Not taking advantage of work benefits.

If you're not taking full advantage of your employee benefits, you're leaving money on the table. Some of the more overlooked, yet incredibly advantageous, benefits include:

Healthcare flexible spending account (FSA). This type of account is a pre-tax benefit account you can use to cover a variety of healthcare products and services, from acupuncture and physical therapy, to vaccines and over-the-counter medicine. You can put up to $US2,550 of tax-free money into this account in 2015, and save about 30% on healthcare expenses with the tax break, WageWorks reports.

Dependent care flexible spending account. If you have young children, dependent care FSAs are worth considering. This account works very similarly to the healthcare FSA, in that you can contribute pre-tax money, but is specific for dependent care services, such as preschool, summer camp, daycare, or before and after school programs.

Commuter benefits. These are often overlooked, but they can save you over $US600 each year, WageWorks tells the Wall Street Journal. The concept is simple: Employees can use pre-tax money from their paychecks to cover mass-transit passes -- including the train, subway, bus, and ferry -- and parking.

It's worth it to research and talk to your human resources department to understand the scope of what's available to you, as these benefits could save you thousands of dollars each year.

Homes are expensive -- start saving for a down payment as early as possible.

4. Not setting aside money for the big, upcoming purchases.

Your 30s are bound to be filled with big purchases -- a home, car, and kids, to name a few -- that require diligent saving.

The best way to prepare for these expenses is to start by creating savings goals, and then set aside money as early as possible. Mint, LearnVest, and You Need A Budget are online tools that allow you to create savings goals and see your progress.

It's important to contribute money towards a retirement fund, but don't forget about and neglect other major expenses. You'll want to have savings if you're planning on having kids -- the average cost to raise a child is about $US245,000, and that doesn't include college -- or looking to buy a home, which often requires significant savings just for the down payment.

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Don't try to match your lifestyle to the top 1%.

7. Trying to keep up with the Joneses.

While living up to your neighbours' or coworkers' standards can be tempting, it can also be detrimental to your finances.

'You have to monitor your spending and limit aspirational purchases,' emphasises Mark Avallone, certified financial planner and president at Potomac Wealth Advisors. 'Just because you see other people enjoying a certain level of a lifestyle doesn't mean you can, or should be doing the same.'

The best way to avoid this pitfall is to create a written financial plan to outline your budget and savings goals. 'Without a written financial plan, there's no destination in mind, and there's no tangible concept of how much is needed to be saved,' says Avallone. 'But if you have structure in your monthly budget, you know what you can and cannot afford.'

The more you can save, the better, but it's important to include some personal luxuries in the spending plan, Avallone notes: 'Everyone's budget should include the essentials, but it should also include fun items. Otherwise, the savings plan will not work. It's very similar to a diet that doesn't allow the person to have a few treats and special meals: If they're not allowed to enjoy those aspects, they will get off the diet entirely.'

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Kids are cute, but you don't have to go all out when it comes to spending.

9. Overspending on the first kid.

When the first kid comes along, what tends to happen is that new parents will overspend on top-of-the-line cribs, bottles, clothes, and nursery accessories, says Brandon Moss, certified financial planner and VP of wealth adviser management at United Capital.

'Spending issues that we tend to see in 20-somethings will level out until the kids come along,' he tells Business Insider. 'And then it explodes.'

You want to raise your child in a comfortable environment, but check yourself before dropping a couple grand on that fancy stroller and draining your savings, as there are bound to be unexpected costs to arise. To get an idea of what you might need to cover, read about the costs new parents didn't see coming.

Life happens, and you'll need to rebalance your investments accordingly.

12. Not revisiting and adjusting your investments.

You can't just 'set and forget' your investments forever. Life happens, and there are times -- particularly big life changes -- when it's smart to make financial adjustments.

For example, if you decide to retire early, you'll need to readjust your time horizon and the amount of risk you choose to take in your portfolio.

As your money grows, and as you get closer to the end of your time horizon, the original portfolio you created may no longer suit your needs -- revisit it every year and adjust it to fit your current situation if needed.

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