Ellen Goodman, the liberal columnist, had a unique policy for corrections. Rather than fixing her errors as she made them, she would run a column at the end of December listing them all for the entire year.

I don’t seem to have accumulated that many, at least this year, but I do have one to note: A reader has pointed out to me that in last week’s column, I quoted a source that said a new tax under Obamacare (one of the 20 or so that law contains) would add a 3.8 percent surcharge on capital gains.

But I left off the rest of the quote, that the tax “applies to any profit that pushes your income over $200,000.” My bad.

That was a useful criticism, as are many I receive. But they don’t have to be. I write what I want, and other people can say whatever they want to about it. If the replies are published, readers are perfectly capable of making up their own minds about who has the better argument.

When I cite a quote or a fact, however, I always try to give a source and a date, so readers can check what I’ve quoted if they want.

Every so often, however, someone doesn’t seem to play the game fairly.

The Portland Press Herald printed a letter last week in which the writer took me to task for citing specific Medicare tax and payment levels for a retired couple who made average salaries during their working lives.

Though I had identified my source, a column in the Washington Examiner on Oct. 21, the writer kept attributing the figures to me, as if I had made them up out of thin air.

And the writer’s conclusion was that I might as well have, because the amount the article cited for an average couple’s Social Security taxes ($150,000) or expected benefits (“more than $350,000”) were in his opinion so far off base as to be “unreal,” even “surreal.”

The couple, he said, would have had to make $80,000 each to pay that much in taxes, and the benefit amount I cited was “unsubstantiated,” “unreal” and “grossly misleading.”

He cited no source for his conclusions, however.

So I reread the original article and verified I had quoted it correctly.

Next, I needed an independent source for the figures.

The Internet quickly yielded a report published this year by the Urban Institute, a center-left think tank, listing Medicare and Social Security payments and benefits across a range of incomes.

And, as hard as this may be for the letter-writer to credit, the Examiner’s figures closely corresponded with the Urban Institute’s report.

The report listed payments and benefits under Social Security and Medicare for selected participants, including a two-earner couple, both of whom made the average U.S. wage in 2011. (The Social Security Administration lists it as $42,979.61, while the report cited it as $43,500, a minor difference.)

Then the report tabulated how much they would have paid in to both programs and then received in total benefits over their projected life spans.

Note that a couple each making $43,000 ($86,000 total) isn’t all that unreal: Two schoolteachers with master’s degrees could do it, and a police officer married to a nurse likely would make more.

But they do not make “$80,000 each,” as my complainant alleged.

Second, the article I cited quoted the amount the couple would receive in Medicare benefits correctly: “More than $350,000″ turned out to be $357,000 if they retired in 2011.

But there was a significant discrepancy in the amount they paid in: The Examiner said it was $150,000 over their productive lifetimes, and the Urban Institute said it would have been just $119,000.

However, that makes the point about the cost of the program even more strongly: The difference between income and taxpayer-subsidized outgo is even greater, rising from $200,000 in the article to $238,000 in the report.

So, it doesn’t look like the Medicare figures I cited in my column were “misleading” after all.

(If you want to see the relevant page from the report, send an email to the address below with “Urban report” as the subject and I’ll send you a copy.)

As a final note, the report’s Social Security figures were even more revealing.

While a one-earner couple making $43,500 and retiring in 2011 paid $299,000 to Social Security and will get back $448,000, and a mid-range two-earner couple making $63,000 paid $434,000 and will get $471,000, the higher-end couple paid $598,000 and will receive $556,000, for a negative rate of return.

That is, they would have been better off putting their money in a savings account paying 1 percent interest than sending it to Social Security.

Perhaps now we can see why younger workers are pessimistic about a “benefit” like that.

M.D. Harmon, a retired journalist and military officer, is a free-lance writer and speaker. He can be contacted at: [email protected]