You can’t blame the surprising jump on the Affordable Care Act or even on healthcare inflation, says Sunit Patel, SVP at Fidelity. Longevity is the culprit. In 2014, the Society of Actuaries released a new mortality table in which the average lifespan of a 65-year-old man jumped from 82 to 85 and that of a 65-year-old woman from 85 to 87. “That’s good news,” Patel notes. “The flip side is that you need to save more.”

Where that money is likely to go is fairly easy to document with some simple math: Once a person goes on Medicare, the most common Medicare supplement plan they purchase, Patel explains, is Plan F at a cost of about $300 per month (costs vary depending where you live) per person. You also have to pay Medicare Part B and Part D premiums, which run about $105 and $30 a month, respectively. All in all, that’s $435 a month or $5,220 a year – times two.

In other words, it’s a relatively fixed cost – one most people don’t seem to be planning for. An earlier Fidelity study said that for three-quarters of couples, being unable to afford the cost of health care in retirement is their top concern. Yet less than one-quarter has factored it into their planning.

That’s a mistake, says J. J. Montanaro, a certified financial planner with USAA. “You have to build it into your plan,” he says. “Then, as you get closer to retirement and put a price tag on [the life you want to live] you can adjust your plan based on these costs.”

So, how should you be thinking about adding this line item to your retirement plan? A few suggestions.

• A little mental accounting never hurts. Mental accounting is the behavioral finance principal at work when humans separate the money they’re amassing into various buckets with different goals. It can help boost savings. This is one reason (taxes are another, more on that in a moment) that putting some money into a Health Savings Account, if you’re eligible, makes sense. It’s also why it’s important to think of health expenses as a distinct fixed cost down the road – like housing, utilities and transportation.
• Add it to the roster when you take something else off. Having just sent my youngest off to college, my days of making 529 contributions will soon be coming to an end. So, I asked Patel: Should I funnel the college saving money into a healthcare bucket instead? “I’ve never thought of it that way,” he said, “but yes. We want to help individuals understand that healthcare is a different expense, but an important expense.” You could do the same when you finish a car payment or retire your student loans.
• If possible, save your HSA funds for later. If you can afford it, it absolutely makes sense to pay for your current healthcare needs out-of-pocket, while allowing your HSA funds to continue to grow. Use them for healthcare in retirement and they won’t be taxed at all. Use them for anything else in retirement and you’ll have to pay income tax at your current rate but no penalty. “At worst, it’s like withdrawing from IRA or 401(k),” Patel says. As far as having too much in the account, he shakes his head. “Individuals don’t have to fear. It’s extremely unlikely that they won’t need it.”