TIPS CPI updates
Each month's CPI-U print sets the TIPS reference CPI two and three months later. This page records each print as it arrives, shows the reference CPI values it fixes, and translates the change into what happens to inflation-adjusted principal. The series is CPI-U, all items, not seasonally adjusted (1982 to 1984 = 100), the index named in the TIPS terms. The seasonally adjusted headline number in news reports will differ.
Monthly prints
| Month | CPI-U (NSA) | Change | Reference CPI it sets |
|---|---|---|---|
| September 2026 | 336.940 | +0.59% | November 2026 daily and December 1, 2026 |
| August 2026 | 334.980 | +0.32% | October 2026 daily and November 1, 2026 |
| July 2026 | 333.918 | -0.01% | September 2026 daily and October 1, 2026 |
| June 2026 | 333.952 | -0.35% | August 2026 daily and September 1, 2026 |
| May 2026 | 335.123 | +0.63% | July 2026 daily and August 1, 2026 |
| April 2026 | 333.020 | +0.85% | June 2026 daily and July 1, 2026 |
| March 2026 | 330.213 | +1.05% | May 2026 daily and June 1, 2026 |
| February 2026 | 326.785 | +0.47% | April 2026 daily and May 1, 2026 |
| January 2026 | 325.252 | +0.37% | March 2026 daily and April 1, 2026 |
| December 2025 | 324.054 | -0.02% | February 2026 daily and March 1, 2026 |
| November 2025 | 324.122 | n/a | January 2026 daily and February 1, 2026 |
| September 2025 | 324.800 | +0.25% | November 2025 daily and December 1, 2025 |
The BLS published no value for October 2025, so the month is absent from the table and the following month shows no change figure.
Recent prints in detail
September 2026 CPI-U: 336.940
The Bureau of Labor Statistics reported the September 2026 CPI-U, all items, not seasonally adjusted, at 336.940. That is a rise of 0.59% from August 2026 and 3.74% above September 2025. The September 2026 print fixes every daily reference CPI in November 2026 and the value on December 1, 2026.
| Date | Reference CPI | Derived from |
|---|---|---|
| November 1, 2026 | 334.98000 | August 2026 CPI |
| November 15, 2026 | 335.89467 | interpolated, day 15 of 30 |
| November 30, 2026 | 336.87467 | interpolated, day 30 of 30 |
| December 1, 2026 | 336.94000 | September 2026 CPI |
From November 1, 2026 to December 1, 2026, reference CPI moves up by 0.585%. Adjusted principal at the start × (336.94000 ÷ 334.98000) gives these examples.
| Adjusted principal at start | Adjusted principal at end | Change |
|---|---|---|
| $10,000.00 | $10,058.51 | +$58.51 |
| $50,000.00 | $50,292.55 | +$292.55 |
| $100,000.00 | $100,585.11 | +$585.11 |
Check of the November 15 value: 334.98000 + (14 ÷ 30) × (336.94000 − 334.98000) = 335.89467.
The September 2026 monthly change of +0.59% follows +0.32% in August 2026, a difference of +0.27 percentage points. Over the three months from June 2026 to September 2026, the index changed +0.89% in total.
The September 2026 value was first saved by this site on October 14, 2026.
August 2026 CPI-U: 334.980
The Bureau of Labor Statistics reported the August 2026 CPI-U, all items, not seasonally adjusted, at 334.980. That is a rise of 0.32% from July 2026 and 3.40% above August 2025. The August 2026 print fixes every daily reference CPI in October 2026 and the value on November 1, 2026.
| Date | Reference CPI | Derived from |
|---|---|---|
| October 1, 2026 | 333.91800 | July 2026 CPI |
| October 15, 2026 | 334.39761 | interpolated, day 15 of 31 |
| October 31, 2026 | 334.94574 | interpolated, day 31 of 31 |
| November 1, 2026 | 334.98000 | August 2026 CPI |
From October 1, 2026 to November 1, 2026, reference CPI moves up by 0.318%. Adjusted principal at the start × (334.98000 ÷ 333.91800) gives these examples.
| Adjusted principal at start | Adjusted principal at end | Change |
|---|---|---|
| $10,000.00 | $10,031.80 | +$31.80 |
| $50,000.00 | $50,159.02 | +$159.02 |
| $100,000.00 | $100,318.04 | +$318.04 |
Check of the October 15 value: 333.91800 + (14 ÷ 31) × (334.98000 − 333.91800) = 334.39761.
The August 2026 monthly change of +0.32% follows -0.01% in July 2026, a difference of +0.33 percentage points. Over the three months from May 2026 to August 2026, the index changed -0.04% in total.
The August 2026 value was first saved by this site on September 11, 2026.
July 2026 CPI-U: 333.918
The Bureau of Labor Statistics reported the July 2026 CPI-U, all items, not seasonally adjusted, at 333.918. That is a fall of 0.01% from June 2026 and 3.36% above July 2025. The July 2026 print fixes every daily reference CPI in September 2026 and the value on October 1, 2026.
| Date | Reference CPI | Derived from |
|---|---|---|
| September 1, 2026 | 333.95200 | June 2026 CPI |
| September 15, 2026 | 333.93613 | interpolated, day 15 of 30 |
| September 30, 2026 | 333.91913 | interpolated, day 30 of 30 |
| October 1, 2026 | 333.91800 | July 2026 CPI |
From September 1, 2026 to October 1, 2026, reference CPI moves down by 0.010%. Adjusted principal at the start × (333.91800 ÷ 333.95200) gives these examples.
| Adjusted principal at start | Adjusted principal at end | Change |
|---|---|---|
| $10,000.00 | $9,998.98 | −$1.02 |
| $50,000.00 | $49,994.91 | −$5.09 |
| $100,000.00 | $99,989.82 | −$10.18 |
Check of the September 15 value: 333.95200 + (14 ÷ 30) × (333.91800 − 333.95200) = 333.93613.
The July 2026 monthly change of -0.01% follows -0.35% in June 2026, a difference of +0.34 percentage points. Over the three months from April 2026 to July 2026, the index changed +0.27% in total.
The July 2026 value was first saved by this site on September 11, 2026.
June 2026 CPI-U: 333.952
The Bureau of Labor Statistics reported the June 2026 CPI-U, all items, not seasonally adjusted, at 333.952. That is a fall of 0.35% from May 2026 and 3.53% above June 2025. The June 2026 print fixes every daily reference CPI in August 2026 and the value on September 1, 2026.
| Date | Reference CPI | Derived from |
|---|---|---|
| August 1, 2026 | 335.12300 | May 2026 CPI |
| August 15, 2026 | 334.59416 | interpolated, day 15 of 31 |
| August 31, 2026 | 333.98977 | interpolated, day 31 of 31 |
| September 1, 2026 | 333.95200 | June 2026 CPI |
From August 1, 2026 to September 1, 2026, reference CPI moves down by 0.349%. Adjusted principal at the start × (333.95200 ÷ 335.12300) gives these examples.
| Adjusted principal at start | Adjusted principal at end | Change |
|---|---|---|
| $10,000.00 | $9,965.06 | −$34.94 |
| $50,000.00 | $49,825.29 | −$174.71 |
| $100,000.00 | $99,650.58 | −$349.42 |
Check of the August 15 value: 335.12300 + (14 ÷ 31) × (333.95200 − 335.12300) = 334.59416.
The June 2026 monthly change of -0.35% follows +0.63% in May 2026, a difference of -0.98 percentage points. Over the three months from March 2026 to June 2026, the index changed +1.13% in total.
The June 2026 value was first saved by this site on September 11, 2026.
May 2026 CPI-U: 335.123
The Bureau of Labor Statistics reported the May 2026 CPI-U, all items, not seasonally adjusted, at 335.123. That is a rise of 0.63% from April 2026 and 4.25% above May 2025. The May 2026 print fixes every daily reference CPI in July 2026 and the value on August 1, 2026.
| Date | Reference CPI | Derived from |
|---|---|---|
| July 1, 2026 | 333.02000 | April 2026 CPI |
| July 15, 2026 | 333.96974 | interpolated, day 15 of 31 |
| July 31, 2026 | 335.05516 | interpolated, day 31 of 31 |
| August 1, 2026 | 335.12300 | May 2026 CPI |
From July 1, 2026 to August 1, 2026, reference CPI moves up by 0.631%. Adjusted principal at the start × (335.12300 ÷ 333.02000) gives these examples.
| Adjusted principal at start | Adjusted principal at end | Change |
|---|---|---|
| $10,000.00 | $10,063.15 | +$63.15 |
| $50,000.00 | $50,315.75 | +$315.75 |
| $100,000.00 | $100,631.49 | +$631.49 |
Check of the July 15 value: 333.02000 + (14 ÷ 31) × (335.12300 − 333.02000) = 333.96974.
The May 2026 monthly change of +0.63% follows +0.85% in April 2026, a difference of -0.22 percentage points. Over the three months from February 2026 to May 2026, the index changed +2.55% in total.
The May 2026 value was first saved by this site on September 11, 2026.
April 2026 CPI-U: 333.020
The Bureau of Labor Statistics reported the April 2026 CPI-U, all items, not seasonally adjusted, at 333.020. That is a rise of 0.85% from March 2026 and 3.81% above April 2025. The April 2026 print fixes every daily reference CPI in June 2026 and the value on July 1, 2026.
| Date | Reference CPI | Derived from |
|---|---|---|
| June 1, 2026 | 330.21300 | March 2026 CPI |
| June 15, 2026 | 331.52293 | interpolated, day 15 of 30 |
| June 30, 2026 | 332.92643 | interpolated, day 30 of 30 |
| July 1, 2026 | 333.02000 | April 2026 CPI |
From June 1, 2026 to July 1, 2026, reference CPI moves up by 0.850%. Adjusted principal at the start × (333.02000 ÷ 330.21300) gives these examples.
| Adjusted principal at start | Adjusted principal at end | Change |
|---|---|---|
| $10,000.00 | $10,085.01 | +$85.01 |
| $50,000.00 | $50,425.03 | +$425.03 |
| $100,000.00 | $100,850.06 | +$850.06 |
Check of the June 15 value: 330.21300 + (14 ÷ 30) × (333.02000 − 330.21300) = 331.52293.
The April 2026 monthly change of +0.85% follows +1.05% in March 2026, a difference of -0.20 percentage points. Over the three months from January 2026 to April 2026, the index changed +2.39% in total.
The April 2026 value was first saved by this site on September 11, 2026.
Reference CPI method
The first day's reference CPI uses the not-seasonally-adjusted CPI-U from three calendar months earlier. Later days interpolate toward the following month's first-day value: reference CPI = first-day value + ((day − 1) ÷ days in month) × (next first-day value − first-day value). The check for each print above substitutes that release's actual numbers. The fraction uses 14 elapsed days on the 15th, not 15 days. The Treasury convention is set out in 31 CFR 356, Appendix B.
The lag uses already published inflation data, so settlement index ratios can be known in advance. An individual security's index ratio divides that day's reference CPI by the security's original reference CPI. Treasury's rounded CUSIP-level values in the official CUSIP table govern actual payments and settlement. The settlement walkthrough shows how an index ratio affects a purchase.
Reading the principal examples
Each example applies the proportional change in reference CPI to a TIPS held across both dates, starting from its inflation-adjusted principal. These are principal adjustments, not market-price changes or cash payments. Actual security values can differ slightly because Treasury rounds each CUSIP's index ratio. An increase accrues to principal. Coupon cash depends on the security's payment dates and coupon rate. A monthly change alone is not an annual tax amount.
Reading a decline in principal
This series includes seasonal price movements. A lower reference CPI reduces inflation-adjusted principal between those dates, but one monthly decline does not determine the next coupon. That payment uses the index ratio on its payment date. The maturity payment cannot be below original face amount. That floor does not protect a purchase premium, the daily balance or the trading price. How TIPS principal adjusts covers these distinctions. Monthly changes in a not-seasonally-adjusted series do not isolate an underlying inflation trend.
Tax treatment of the annual adjustment
For taxable holdings, a principal increase over the applicable annual holding period is generally reported as original issue discount even before it is paid in cash. A negative annual calculation is a deflation adjustment, which generally offsets interest from that security under the IRS rules. A negative monthly CPI print by itself does not establish either a deduction or a tax bill. Account type, holding dates and purchase adjustments matter. See IRS Publication 1212, Inflation-Indexed Debt Instruments and the site's worked tax example.
Sources: BLS series CUUR0000SA0, BLS Consumer Price Index and TreasuryDirect TIPS and CPI data. Reference CPI figures here are computed from the published index and rounded to five decimals. Treasury's published table governs.
