I Bond Early Withdrawal Penalty Calculator

An I-Bond early withdrawal penalty calculator computes the 3-month interest forfeiture for Treasury Series I Savings Bonds redeemed before holding 5 full years, and converts the haircut into a net effective yield for comparison with alternative fixed-income investments.

How the I Bond Early Withdrawal Penalty Works

The U.S. Treasury imposes a 3-month interest penalty on I-Bond redemptions before 5 years. The penalty is calculated as 3 months of interest at the most recent composite rate (fixed rate + inflation rate component). I-Bonds cannot be redeemed at all in the first 12 months. After 5 years of holding, the penalty disappears entirely and all accrued interest is yours (source: treasurydirect.gov).

Composite Rate Mechanics

The I-Bond composite rate has two components: a fixed rate set at issuance and locked for the life of the bond, plus an inflation rate based on the CPI-U semi-annual change. The Treasury announces new rates every May 1 and November 1. For bonds issued 1 May 2026 through 31 October 2026 the Treasury set a fixed rate of 0.90% and a composite rate of 4.26%. The composite rate is computed as: fixed + 2 × inflation + (fixed × inflation), then floored at zero.

When Penalty Redemption Still Makes Sense

If newer I-Bonds offer a higher fixed rate (the May 2026 issue carries 0.90% versus the 0.00% attached to most 2021-2022 bonds), strategic redemption + repurchase can lift long-term yield even after the 3-month penalty haircut. This is most valuable for bonds with a 0.00% or low fixed rate purchased during 2021-2022. Run the numbers: only swap if the new fixed rate is at least 0.50% higher than your current locked rate.

When Does Your I-Bond Penalty Actually End?

Two dates matter and people routinely confuse them. The 12-month lockup runs from your issue date — before it passes you cannot redeem at all, with a narrow exception for federally declared disaster areas. The 3-month penalty then applies from month 13 until you have held the bond for five full years; redeem in that window and you forfeit the three most recent months of interest. A bond bought in March 2023 becomes redeemable in March 2024 and penalty-free in March 2028. One detail worth knowing: I-Bond interest posts on the first day of each month, and the penalty is taken from the most recent three months, so redeeming just after a new month posts recovers slightly more than redeeming a few days earlier. Updated 2026-08-03.

Time the Exit to Your Rate Period, Not the Calendar

The penalty is not a fixed dollar amount — it is the last three months of interest at whatever rate applied during those months, which means the cost of leaving early swings with your own rate cycle. Your composite rate resets every six months from your purchase month, not in January or on the Treasury's May and November announcement dates. Buy in September and your periods run September–February and March–August, so a rate announced in May does not reach you until September. The consequence is straightforward and most holders miss it: if you are currently inside a low-rate six-month period, your exit is cheap, because the three months you forfeit are being valued at that low rate. If you are inside a high-rate period, the same redemption costs materially more. On a $10,000 bond, three months at a 3% composite forfeits roughly $75; at a 6% composite it forfeits roughly $150 — same bond, same rule, double the cost purely from timing.

Put the two timing rules together for the cheapest possible exit. First, work out which six-month period you are in by counting from your issue month. Second, if a low-rate period is about to be replaced by a higher one, redeeming before the switch means the penalty is drawn from the cheap months. Third, redeem just after the first of the month, once the new month's interest has posted, since interest credits monthly rather than daily and cashing on the 28th pays the same as cashing on the 2nd. And check the calendar against five years from your issue date before doing any of this — once you cross that mark the penalty disappears entirely, so waiting a few extra weeks usually beats any timing trick. Confirm your bond's current and next composite rate in your TreasuryDirect account before deciding. Updated 2026-08-12.

I-Bond vs T-Bill vs TIPS After the Penalty

The 3-month penalty only matters relative to what else your cash could do. Treasury bills carry no penalty at all and can be held to a 4, 8, 13, 26 or 52-week maturity, so for money needed inside a year they beat a penalised I-Bond redemption outright. TIPS adjust principal with CPI rather than paying an inflation-linked composite rate, and trade on the secondary market — meaning they can be sold any time but at a capital loss if rates have risen. I-Bonds are the only one of the three that cannot lose nominal value. All three share the same state and local tax exemption; only I-Bonds let you defer federal tax until redemption. Use the effective net yield produced above, not the headline composite rate, when comparing against a T-bill quote. Rates for every Treasury security are published at treasurydirect.gov. Updated 2026-08-03.

Last updated 2026-08-03. Sources: treasurydirect.gov, Treasury rate announcements.