The standard deduction rose in 27 of the 29 years to 2017, and ended worth 2 percent more than it started

Twenty seven increases in twenty nine years. That is the record of the basic standard deduction between the 1988 tax year and the 2017 tax year, and it produced almost nothing. Measured in constant 2025 dollars, a single filer's standard deduction was worth $8,164 in 1988 and $8,340 in 2017. Thirty years of annual raises, and the number finished 2.2 percent higher than it started.

That is what indexation does. It is supposed to do exactly that, and the fact that it worked is invisible in every reference table on the subject, because the reference tables publish the nominal column and stop.

The full nominal series is below, and so is the deflated one. What the deflated series shows is a history with three real events in it and a long stretch of nothing in between: a collapse that ran from 1977 to 1984, a repair in 1988, and a near doubling in 2018 that a second law extended and enlarged in 2025.

What has the standard deduction been, year by year, since 1970?

The basic standard deduction has risen from $1,100 for a single filer in 1970 to $16,100 in 2026. The joint amount has risen from $1,100 to $32,200. Head of household did not exist as a separate standard deduction amount until the 1988 tax year, and before that the table carries the same figure as a single filer.

The 1970 to 2024 amounts are the Tax Policy Center's compilation of IRS Revenue Procedures. The 2025 and 2026 amounts are read from Rev. Proc. 2025-32, sections 3.01 and 4.14. The constant-dollar column is our own calculation from the Bureau of Labor Statistics CPI-U annual averages, expressed in 2025 dollars. The whole series, including the ratio columns discussed further down, is available as a CSV.

The 2026 row has no constant-dollar figure because the 2026 annual average does not exist yet. For reference, the CPI-U for June 2026 stood at 333.952 against a 2025 annual average of 321.943.

Why did the standard deduction lose more than a third of its value between 1977 and 1984?

Because Congress fixed it in dollars and then left it there through the worst inflation of the postwar period. The single-filer amount was $2,300 in every year from 1979 through 1984. Prices rose 43 percent over the same span. In constant 2025 dollars the deduction fell from $11,688 in 1977 to $7,127 in 1984, which is the lowest reading in the entire series.

The 1977 peak was not an accident of the data. The Tax Reduction and Simplification Act of 1977 rewrote section 63 to replace the standard deduction with what the statute then called the zero bracket amount, and it set that amount at $2,200 for a single filer against $1,700 the year before. The mechanism was different from the one in force now. The zero bracket amount was built into the tax tables rather than subtracted before them, and taxpayers who itemized had to add back the unused portion. The amendment notes to section 63 preserve the repealed text, including the definition of the unused zero bracket amount and the transitional rules that went with it.

What matters for the series is not the plumbing. It is that the number was a flat dollar figure with no automatic adjustment, in a period when the price level nearly doubled. Every year Congress did not act, the real value fell. Between 1979 and 1984 Congress did not act five times running.

This is the same arithmetic that produced bracket creep, and it was fixed in the same legislation.

What did the 1986 Tax Reform Act actually change?

Section 102(a) of the Tax Reform Act of 1986 restored the name and rebuilt the structure. It replaced the heading of section 63(c) with "Standard deduction", replaced the heading of section 63(d) with "Itemized deductions", and set new basic amounts effective for taxable years beginning after 31 December 1986, with a transitional rule for 1987 that a 1990 act later struck as spent.

Three things arrived with it, and all three are still in force.

The first is a separate head of household amount. Section 63(c)(2)(B) still reads "$4,400 in the case of a head of household", which is the 1988 figure, untouched in the statute for thirty eight years and carried forward only by the inflation adjustments layered on top of it. Section 63(c)(2)(C) still reads "$3,000 in any other case". Those two numbers are the base of the entire modern table.

The second is indexation. Section 63(c)(4) instructs that each of those dollar amounts be increased by the cost-of-living adjustment determined under section 1(f)(3), measured from calendar year 1987. That is the provision which turned $3,000 into $6,350 by 2017 and did nothing else.

The third is the additional amount for age and blindness. Section 63(f) grants $600 for a taxpayer who has attained 65 before the close of the taxable year, and another $600 for blindness, with the figure substituted to $750 for an individual who is not married and not a surviving spouse. Indexed forward, those are the $1,650 and $2,050 in Rev. Proc. 2025-32. The statutory definition of blindness has not moved either: central visual acuity no better than 20/200 in the better eye with correcting lenses, or a visual field no wider than 20 degrees.

When did the joint standard deduction become exactly twice the single amount?

In the 2003 tax year. From 1988 through 2002 the joint amount was a separate statutory figure worth less than two single deductions, which is a marriage penalty measurable to the dollar. It was $1,000 in 1988 and it had widened to $1,550 by 2002. Two laws closed it and a third made the closure permanent.

Read down the ratio column and the history is unmistakable. In 1988 a joint filer received 1.667 times the single amount. In 2002 the ratio was still 1.670. In 2003 it was exactly 2.000, and it has been exactly 2.000 in every year since.

The statutory route is visible in the amendment notes. The Economic Growth and Tax Relief Reconciliation Act of 2001 struck the flat "$5,000" out of section 63(c)(2)(A) and substituted "the applicable percentage of the dollar amount in effect under subparagraph (C)", with a phase-in table, and the same section struck the separate $2,500 amount that married individuals filing separately had carried until then. The Jobs and Growth Tax Relief Reconciliation Act of 2003 inserted a table item for 2003 and 2004 that pulled the applicable percentage straight to 200. The Working Families Tax Relief Act of 2004 then rewrote the subparagraph to name the percentage outright and deleted the phase-in table.

Section 63(c)(2)(A) now reads "200 percent of the dollar amount in effect under subparagraph (C) for the taxable year". The joint standard deduction is not a number Congress sets. It is a function of the single-filer number, and it carries one arithmetic consequence worth noticing: because the single amount must be rounded to a multiple of $50, the joint amount has been an exact multiple of $100 in every year since 2003.

Head of household drifted the other way. Its ratio to the single amount was 1.467 in 1988 and 1.476 by 2016. Since 2018 it has been exactly 1.5, because the 2017 and 2025 laws both set the two figures as a clean three-to-two pair.

How much did the 2017 law raise the standard deduction?

By 84.5 percent in real terms, in a single year, which is the largest one-year move in the series by a wide margin. The single-filer amount went from $6,350 to $12,000, worth $8,340 and $15,385 respectively in 2025 dollars. Nothing else in the series comes close.

Section 11021(a) of the 2017 act added section 63(c)(7), which did not amend the base amounts at all. It left $3,000 and $4,400 sitting in subparagraphs (C) and (B) and instructed that paragraph (2) "shall be applied" by substituting $18,000 and $12,000 for the taxable years it covered. That drafting choice is why the old numbers are still in the statute, and it is why the increase was built to vanish rather than to be repealed. Section 63(c)(7) applied only to taxable years beginning after 31 December 2017 and before 1 January 2026. Absent further legislation, the 2026 tax year would have reverted to the indexed 1988 base.

The same act made a quieter change with a longer tail. Section 11002(d)(1)(K) altered the reference in section 63(c)(4)(B) so that the adjustment runs off the chained consumer price index rather than the ordinary one. The chained index rises more slowly. Applied to the standard deduction, and to every other indexed threshold in the code, that is a permanent and compounding reduction in the real value of an inflation adjustment, and it is the same mechanism we traced through the Social Security formula in how the cost-of-living adjustment is calculated.

The effect of the doubling on filing behaviour was immediate and is documented in the IRS data. The share of returns claiming itemized deductions fell from 30.6 percent to 9.5 percent, which we covered in who still itemizes after the 2017 tax law.

What did the 2025 law change?

It made the increase permanent and then added 5 percent on top. Section 70102 of Public Law 119-21, enacted 4 July 2025, struck the words "and before January 1, 2026" from section 63(c)(7), replaced $18,000 with $23,625 and $12,000 with $15,750, and moved the inflation base year from 2017 to 2024. The amendments apply to taxable years beginning after 31 December 2024.

The size of the increase is easy to miss because it was retroactive. In October 2024 the IRS had already published the 2025 amounts in Rev. Proc. 2024-40: $15,000 single, $22,500 head of household, $30,000 joint. Nine months later the enacted figures were $15,750, $23,625 and $31,500. Section 3.01 of Rev. Proc. 2025-32 removes the superseded table and prints the replacements.

Divide one set by the other and every filing status returns the same answer. 15,750 over 15,000 is 1.05. 23,625 over 22,500 is 1.05. 31,500 over 30,000 is 1.05. The law did not adjust the amounts for anything measured. It marked them up by a flat twentieth.

The base-year reset matters more than the 5 percent and will stay invisible for years. Section 63(c)(7)(B)(ii)(II) now measures the adjustment from calendar year 2024 rather than 2017, which means the seven years of price change already embedded in the pre-2025 figures are no longer part of the calculation at all. Every future increase compounds off $15,750 and $23,625.

The combined result is that the 2025 tax year carries the highest real standard deduction in the history of the provision, $15,750 in 2025 dollars, against a previous high of $15,425 in 2020. The intervening years were an erosion. Chained indexation lagged the 2021 and 2022 price surge, and the real value fell to $14,246 in 2022, which was 7.4 percent below its 2018 level.

How is the annual increase computed, and can the published figure be checked?

Partly. The formula is fully specified in statute and the arithmetic is reproducible, but the price data it runs on is deliberately frozen at a vintage that no longer exists in the published series, so an exact after-the-fact reproduction is not available for every filing status.

The mechanism runs like this. Section 63(c)(7)(B)(ii) increases $15,750 and $23,625 by the cost-of-living adjustment determined under section 1(f)(3), substituting 2024 for 2016, and rounds any increase down to the next lowest multiple of $50. Section 1(f)(3)(C) states what that substitution means when the base year falls after 2016: the comparison runs against the chained index for the base year. Section 1(f)(6)(B) defines the chained index for a calendar year as the average of the twelve months ending 31 August of that year.

For the 2026 tax year the twelve months to August 2025 average 177.19450, against 173.01583 for the twelve months to August 2024. That is an increase of 2.4152 percent. Applied to $15,750, the raw increase is $380.39, which rounds down to $350 and produces $16,100. That matches Rev. Proc. 2025-32 exactly. The joint figure follows from the 200 percent rule at $32,200, and matches as well.

The head of household figure does not. Applied to $23,625, the raw increase is $570.59, which rounds down to $550 and produces $24,175. The revenue procedure says $24,150.

The $25 is not an error in either direction. Section 1(f)(6)(A) fixes the price data to "the latest values so published as of the date on which such Bureau publishes the initial value" of the chained index for the August of the preceding calendar year. The IRS computed the 2026 figures on the chained index as it stood in mid-September 2025. The Bureau of Labor Statistics documents that the chained index "is issued first in preliminary form" and "will be subject to multiple revisions, with the final index published 10-12 months after the initial estimate". Most of the twelve months in the 2025 window were preliminary when the revenue procedure was written and have been revised since.

So the honest statement is this. The 2026 standard deduction is checkable in method, and it reproduces exactly for two of the three filing statuses from currently published data. The third differs by one rounding step, and the statute is the reason. A figure computed under section 1(f) cannot be re-derived from the current series once the underlying index has been revised, which is by design rather than by accident, because a tax threshold that moved every time a price index was revised would be unadministrable.

Is the $6,000 senior deduction part of the standard deduction?

No. It is a separate deduction added to section 151 by the same 2025 law, it is available whether or not you itemize, it phases out with income, and it expires. Reading it as an increase in the standard deduction for people over 65 gets the arithmetic wrong in three places.

Section 70103 of Public Law 119-21 added section 151(d)(5)(C). It allows $6,000 for each qualified individual, defined as the taxpayer if aged 65 before the close of the taxable year and, on a joint return, the spouse if the spouse is also 65. The allowance is reduced by 6 percent of modified adjusted gross income above $75,000, or $150,000 on a joint return, so it runs out at $175,000 and $350,000 respectively. A Social Security number is required on the return for each qualified individual. The subparagraph applies only to taxable years beginning before 1 January 2029.

The existing additional standard deduction for age is untouched and continues alongside it. For 2026 that is $1,650, or $2,050 for an unmarried individual who is not a surviving spouse, under section 63(f) as adjusted. The two provisions stack. They are not the same provision, and only one of them is scheduled to disappear.

What this series does not show

The table is the basic standard deduction. It is not what any particular household actually deducted. A filer aged 65 adds the section 63(f) amount on top. A dependent is capped by section 63(c)(5), which for 2026 limits the basic amount to the greater of $1,350 or $450 plus earned income. A married individual filing separately receives nothing at all if the other spouse itemizes, under section 63(c)(6)(A), and nonresident aliens, estates and trusts receive nothing in any case.

The constant-dollar column is a choice rather than a fact. It deflates by the CPI-U annual average, which is the standard general-purpose price index and is not the chained index the tax code itself uses. Deflating by the chained index would flatten the post-2018 erosion somewhat. We used the CPI-U because the question the column answers is what the deduction was worth to a household, not what the code says it was worth, and the underlying data is linked so that anyone preferring the other basis can rebuild it.

One further caution applies to the 1970 to 1976 rows. Those figures come from a regime with a percentage standard deduction and a low-income allowance running alongside each other, and the single number in the table is a maximum rather than an amount every filer received. The Tax Policy Center compiles them on that basis and flags it. Treat the pre-1977 rows as the ceiling of the provision rather than as a typical deduction.

Frequently asked questions

What is the standard deduction for 2026? $16,100 for single filers and for married individuals filing separately, $24,150 for heads of household, and $32,200 for married couples filing jointly. Add $1,650 for each of age 65 and blindness, or $2,050 each if you are unmarried and not a surviving spouse. The figures are in section 4.14 of Rev. Proc. 2025-32.

What was the standard deduction for 2025? $15,750, $23,625 and $31,500. Tables published before July 2025 show $15,000, $22,500 and $30,000, which the One Big Beautiful Bill Act superseded retroactively. Section 3.01 of Rev. Proc. 2025-32 removed the earlier table.

When was the standard deduction created? In 1944, according to the Tax Policy Center's notes on its historical series. From 1944 to 1969 it equalled 10 percent of adjusted gross income up to a maximum of $1,000. The provision was renamed the zero bracket amount in 1977 and restored to the name standard deduction by the Tax Reform Act of 1986.

Has the standard deduction ever been cut? Once in nominal terms, in 1971, when the single amount fell from $1,100 to $1,050. In real terms it has fallen far more often. Of the 55 year-on-year changes from 1971 to 2025, the constant-dollar value declined in 30, most severely between 1977 and 1984.

Why is the married filing jointly amount always exactly double the single amount? Because section 63(c)(2)(A) defines it that way. It has read "200 percent of the dollar amount in effect under subparagraph (C)" since a 2004 amendment, and the ratio has been exactly 2.000 since the 2003 tax year. Before that the joint amount was set separately and was worth less than two single deductions.