Starting Monday, companies around the country will enter "open enrollment," the short window when employees get to switch their health insurance plans. In addition to regular price increases across the board, anyone shopping for family coverage this year can expect a new slate of expenses. But with calculated plan shopping, a married couple could actually come out ahead.

An increasing number of companies are raising insurance charges to cover a spouse and hiking family deductibles on top of co-pay and premium increases for everyone, single and married alike. Employers are covering just 50% of the cost to cover a spouse and children for the 2011 plan year the lowest amount to date, says Thomas Harte, a board member with the National Association of Health Underwriters. That s partly why family plan premiums that employees will have to pay are expected to rise to $4,400 per year, on average a 12.4% increase over current costs, according to human resource consultancy Aon Hewitt. With so much money at stake, all of a sudden, it s become much more important to make the right decision, says Sheryl Garrett, a fee-only certified financial planner. Choosing the wrong plan could costs thousands extra.

On top of that, around 10% of employers are expected to add a surcharge to cover a spouse who could otherwise be covered by his or her employer. That s double the number that do so now, says Kristen Stagaman, principal with Mercer s health and benefits business. And as employers continue to draw a distinction between benefits for their immediate employees and benefits for family members, the trend will continue, says Karen Frost, health and welfare outsourcing leader at Aon Hewitt.

Before you pick a plan, consider the following four costs and their impact on your family.

Premiums

Until this year, most companies charged flat premiums for family coverage. But now, more companies are charging per participant, says Stagaman. An employee on a plan alone will pay on average $1,010 in premiums in 2011. Add a spouse who might otherwise be covered by his employer, and that fee could climb as high as $4,900. Children are a relative bargain: Adding two raises the single premium by only around $800, on average.

Although it might be less complicated for families to be on one plan, consider splitting up. Compare the cost for one spouse to fly solo on his employer s plan, while the other carries the kids. More so than in the past, the cheapest option could likely be separate plans, says Stagaman. Sticking with separate plans in 2011, a married couple could save about $1,000. All else held equal, the parent with the most affordable combination of family premium and family deductible should add the children to their plan.

Oh, and if you re tempted: Don t lie about your spouse s eligibility for his own insurance. Employers will ask for the name of your spouse s employer, and companies are verifying more these days. They might very well research that company s health insurance offerings, and if you get caught, at the very least your premiums could go up. In the worst case scenario, you could lose your job.

What you pay at the doctor s office

One out of every nine employers plans to increase co-pays by more than 15%, according to a Mercer survey. And 35% plan to raise deductibles by the same amount, bringing the average family deductible what you pay for doctor visits, any hospitalization and other services before insurance kicks in to at least $2,150.

But these increases aren t easy to spot with a cursory glance. An employer might hold premiums steady and raise deductibles, says Thomas Harte, a board member with the National Association of Health Underwriters. In some cases, the in-network deductible might be small, but see a doctor outside of your plan s network, and you ll pay for it. If your must-see specialist isn t in your plan in some specialties like dermatology, gynecology or psychiatry, doctors are apt to take fewer insurance plans you could have a steep deductible hurdle to get over before your insurer ponies up.

Higher deductibles and co-pays won t hurt if you re part of a family that rarely gets sick and has no long-term health issues, says Harte. In fact, for the lucky, healthy few, it may help: Plans with higher deductibles will have lower premiums, he says.

Out-of-pocket costs at hospitals

Not all hospital visits can be anticipated, but employees who know or suspect they will be in the hospital next year for surgery or childbirth should determine which spouse s plan will keep their out-of-pocket expenses the lowest. Most health plans cover just 80% of hospitalization costs, down from 90% a few years ago. At the same time, hospital-stay deductibles are expected to rise some may double to as much as $2,000 in 2011. But if you re willing to pay higher premiums, you might get a plan that covers 90% to 100% of those costs. If you know you ll be checking in, that charge could be worth it. For a Caesarean section birth, for example, a typical plan with 90% coverage would save $800 in hospital costs compared to a lower coverage plan, even after accounting for the higher premiums.

If you do have a surgery planned for 2011, before you switch, ask the new insurance company if it will be covered immediately. Pre-existing conditions clauses could kick in and delay coverage. If that s the case, many plans merely require a three-month waiting period before the surgery would be covered, says Garrett.

Prescription costs

When it comes to prescription drugs, there s no uniformity among plans and pricing. One insurer might classify much-used medications like Adderall, Lipitor or Yasmin as third tier, which makes the co-pay the highest. Your spouse s plan, on the other hand, might list these same drugs as second tier, which could save $250 or more per year. Average co-pays for first-tier drugs are $11, but hit $28 in the second and $49 in the third tier, according to Kaiser, and insurance companies list their tier classifications on their web sites.

That s easy enough to calculate. The bigger potential cost to watch for this fall is the switch to what s called prescription co-insurance. More plans are requiring patients to pay a percentage of a drug s cost, rather than the flat co-pay, says Harte. For some medications, you d pay 30% of the cost; for others, you d pay 50%. That AdderallXR you paid $49 for each month in 2010, thanks to your co-pay, could cost about $113.50 per month in 2011; a Lipitor refill would bump up to $55 in 2011. Given the regularity of prescription costs, if you have a choice between your plan and your spouse s, this feature may be more important than lower premiums or higher deductibles.