The line comes from one letter. Leo Mattersdorf, who prepared Einstein’s tax returns, wrote to Time in February 1963 describing a lunch at the Einsteins’ Princeton home where the professor said, with his “inimitable chuckle”, “The hardest thing in the world to understand is income taxes.” Einstein had died in 1955, so the account is posthumous and unverifiable. Quote Investigator ↗ confirms Mattersdorf really was Einstein’s accountant and friend, and concludes the anecdote’s accuracy depends on his memory and veracity.
“The Hardest Thing in the World to Understand Is Income Taxes” attributed to Albert Einstein by his accountant Leo Mattersdorf in a letter to Time, 22 February 1963, almost eight years after Einstein’s death. No contemporaneous source is known. Traced by Quotle.info.
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Provenance
The source
Earliest documented source
Letters, Time magazine, 22 February 1963
Written by
Leo Mattersdorf of New York City, who wrote: “From the time Professor Einstein came to this country until his death, I prepared his income tax returns and advised him on his tax problems.”
Timing
Einstein died in April 1955. The letter appeared in 1963 — there is no record of the remark published in his lifetime.
How Wikiquote files it
Under “Attributed in posthumous publications” — not among the sourced quotations, and not among the misattributed ones
One year while I was at his Princeton home preparing his return, Mrs. Einstein, who was then still living, asked me to stay for lunch. During the course of the meal, the professor turned to me and with his inimitable chuckle said: "The hardest thing in the world to understand is income taxes." I replied: "There is one thing more difficult, and that is your theory of relativity." "Oh, no," he replied, "that is easy." To which Mrs. Einstein commented, "Yes, for you."
Leo Mattersdorf, letter to Time, 22 February 1963
Quote Investigator ↗ identifies the origin as Leo Mattersdorf’s letter in Time of 22 February 1963 and reproduces it in full. Its conclusion is careful: “The earliest known citation is after Einstein’s death, and the accuracy of the anecdote depends on the memory and veracity of Leo Mattersdorf.”
The relationship is not in doubt, which is what keeps this at “attributed” rather than “disputed”. Quote Investigator cites Mattersdorf’s 1952 book Insight into Astronomy, which thanks Einstein for reading the manuscript, and a New York Times obituary of 27 August 1985 recording that Einstein “was an accounting client of Mr. Mattersdorf for many years”.
We checked the Wikiquote page for Albert Einstein ↗ in full source form. It carries this line in the section “Attributed in posthumous publications”, names Mattersdorf as the attributor, and dates the Time letter to 22 February 1963 — agreeing with Quote Investigator on every point.
The version usually seen today is slightly different again: “the Income Tax” rather than “income taxes”. Quote Investigator’s earliest instance of that variant is a March 1968 article in The AOPA Pilot, and it is the form that later reached the IRS’s own website.
The only text of this remark is inside Leo Mattersdorf’s 1963 letter to Time, first published well after 1930, so the wording is treated as in copyright. If you quote it, attribute it as Mattersdorf reported it rather than as documented Einstein.
Rights status is our research, not legal advice — and copyright varies by country and edition. For commercial or published use, confirm with the rightsholder. See terms.
Fact-check
What to watch for
Einstein may well have said it. What he certainly never did was say it on the record.
✕
The usual claimA documented Einstein quotation Overstated
There is no contemporaneous source. Everything traces to one letter published almost eight years after his death, and Quote Investigator says so plainly ↗: the accuracy depends on one man’s memory.
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The wording in circulation“The hardest thing in the world to understand is the Income Tax” Paraphrase
Mattersdorf wrote “income taxes”. The singular “the Income Tax” variant appears from 1968 onward and is the more common modern form — it even reached a tax-quotes page on IRS.gov.
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Who reported itLeo Mattersdorf Context
Not a fabricator on any available evidence: an accountant and amateur astronomer who really did prepare Einstein’s returns, whose 1952 astronomy book Einstein read in manuscript, and whose 1985 New York Times obituary confirms the professional relationship.
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Do not confuse it with“This is a question too difficult for a mathematician” Context
A different Einstein tax remark — and a much better documented one, reported by the Associated Press in March 1944 while he was alive. Quote Investigator covers it separately ↗.
The joke is irresistible because of who is telling it: the man who explained gravity throwing up his hands at a tax form. It has been used for that purpose for sixty years, and by 2011 it was sitting on the IRS’s own website under a tax-quotes heading — an official page citing an anecdote no one can source.
What is genuinely interesting is the second half of Mattersdorf’s story, which almost never gets quoted. When he told Einstein that relativity was harder than taxes, Einstein said no, relativity was easy — and Mrs. Einstein cut in: “Yes, for you.” The punchline belongs to Elsa.
“Oh, no,” he replied, “that is easy.” To which Mrs. Einstein commented, “Yes, for you.”
Read the full story
Mattersdorf was more than a tax preparer. He chaired the Amateur Astronomers Association in New York and wrote Insight into Astronomy (1952), whose acknowledgements thank Einstein for reading the manuscript and sitting down with him to offer suggestions. Quote Investigator also cites a 2007 account describing a 1938 gift of a telescope from Einstein to Mattersdorf.
That is why this record says “attributed” and not “disputed”. There is no reason to think Mattersdorf invented the lunch. There is simply no way to check it — and on a site about provenance, those are different claims.
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Filed under
More provenance-checked quotes on the same theme, each with its reuse status.
Albert Einstein reshaped physics with special relativity (1905), general relativity (1915) and his work on the photoelectric effect, for which he received the 1921 Nobel Prize. He emigrated from Germany in 1933 and spent his remaining years at the Institute for Advanced Study in Princeton, New Jersey, where his tax returns were prepared by an accountant named Leo Mattersdorf. His enormous fame makes him the most quoted — and the most misquoted — scientist who ever lived.
For writers & researchers
Cite this
The primary source (Chicago)
Leo Mattersdorf, letter to the editor, "Letters: Feb. 22, 1963," Time, February 22, 1963.
This verification page
Quotle.info. “Who really said ‘The Hardest Thing in the World to Understand Is Income Taxes’?” Last verified 30 Aug 2026. https://quotle.info/who-said/the-hardest-thing-in-the-world-to-understand-is-income-taxes/