These estimates are actually much lower than the CBO's already-low ones from last year. Back then, it thought gradually increasing the Medicare age to 67 would save $113 billion by 2023. That's not a lot in the grand scheme of a $16 trillion economy that will be even bigger 10 years from now, but it's a whole lot more than what the CBO thinks now. So what changed?

The CBO realized that it overestimated how much Medicare spends on typical 65 and 66 year-olds. Its old estimates looked at average Medicare spending for all 65 and 66 year-olds. But some disabled and terminally ill patients get Medicare before they turn 65, and that wouldn't change if we raised the age to 67. So increasing the Medicare age eliminates Medicare benefits for the healthiest 65 and 66 year-olds, but not the sickest ones.

And even cutting Medicare benefits isn't the same as cutting government benefits. With Obamacare kicking in, some 65 and 66 year-olds would get Medicaid or exchange subsidies if they couldn't get Medicare. This other federal healthcare spending would offset a big chunk of whatever Medicare savings there were. It's federal cost-shifting, not cost-saving.

Now, it is true that Social Security spending would fall a bit too. If they couldn't get Medicare, some 65 and 66 year-olds would postpone retirement to keep their employer-provided healthcare. But not very many. As the CBO points out, most people retire when they want to, not when they can get Medicare. That means increasing the Medicare age wouldn't increase the labor force all that much.

Raising Medicare age seems like an obvious idea, because it's mentioned so often. But what exactly is so obvious about its benefits? Before Obamacare, it would have just shifted healthcare costs from the government to the healthiest seniors. That's not just morally questionable. It's also bad economically, since their private insurers would cost more than Medicare. After Obamacare, it would just shift healthcare costs from one part of the government to another — and some seniors would lose coverage altogether. That's worth $19 billion over ten years?

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