Healthcare costs have been going up for a long time. The Centers for Medicare & Medicaid Services reported annual health spending – healthcare paid for through private health insurance, Medicare, Medicaid, or out-of-pocket spending by businesses, households and governments – in the United States averaged $3.3 trillion in 2016.

That's about $10,348 per person. It's a significant amount even before you consider the median income in the United States was about $57,600 that year.

Here's another perspective: Healthcare spending was equal to almost one-fifth (17.9 percent of GDP) of everything the United States economy produced during 2016 (Gross Domestic Product – GDP – measures the value of all goods and services produced in a country). That's more than U.S. manufacturing produced (11.7 percent of GDP) during 2016. Add in retail (5.9 percent of GDP) and the total is just shy of spending on healthcare.

The cost of healthcare is important not just because it's high, but because it's a critical aspect of retirement planning. A retirement plan is built around a horizon, which is the number of years you expect retirement to last. It's a difficult number to think about because it's a reflection of how long you expect to live.

In general, the planning horizon for women should be longer than the planning horizon for men. Women tend to live longer, and that means their healthcare costs may be considerably higher. About $79,000 higher, according to one estimate that found a healthy 55-year-old woman could pay almost $523,000 in healthcare expenses (Medicare Parts A, B, D, a supplemental policy F, dental, and all out-of-pocket expenses) during retirement.

There are a variety of approaches that may help cover the expense – even if you're closing in on retirement. A retirement planning strategy that factors in healthcare expenses with an appropriate planning horizon can help improve financial stability in your later years.