Promo Float
Make idle cash work harder during a 0% APR window. Free, no signup, no affiliate links.
Rates last updated · 2026-05-09 Where these come from
Cards
Add every card with a 0% promo or potential balance carry. Distinguish purchase APR from BT APR — the tool prevents the #1 mistake of charging direct purchases to a 0%-on-BT-only card.
Est. $25 · 1% + interest at active APR · verify on statement
Cash accounts
Where your liquid cash currently sits. Used for the Rate Check (best alternative) and Triage (payment paths).
Bills (optional)
One-time or recurring bills you need to route. Skip this section if you just want cash parking recommendations — it's only needed for payment-path analysis.
Available 0% APR cards
The top no-annual-fee 0% APR cards currently on the market — verified against issuer pages. Open one to start a 0% window of your own.
As of 2026-05-09
Wells Fargo Reflect
personalWells Fargo
Purchase promo
21 mo
BT promo
21 mo · 3% fee
5% after 120 days
Annual fee
None
Credit score
670+
Longest purchase promo on the market. BT fee is 3% if transferred within 120 days, then 5%. Requires on-time payments to keep the full 21 months.
View offer →U.S. Bank Shield Visa
personalU.S. Bank
Purchase promo
21 mo
BT promo
21 mo · 5% fee
Annual fee
None
Credit score
670+
Replaces the discontinued U.S. Bank Visa Platinum (closed to new applications March 2025). 21 billing cycles 0% on purchases + BT, flat 5% BT fee, $20/yr statement credit for 11 consecutive months of purchases.
View offer →BankAmericard
personalBank of America
Purchase promo
21 mo
BT promo
21 mo · 5% fee
Annual fee
None
Credit score
670+
21 billing cycles 0% on purchases + BT (transfers must complete within 60 days). Flat 5% BT fee. No penalty APR.
View offer →Verify terms on the issuer's page before applying — promo lengths, BT fees, and credit requirements change frequently. Applying for new credit affects your credit score; space applications at least 6 months apart. No affiliate relationships — these links go straight to the issuer. Card rankings are by promo length only.
Vehicle comparison
Window: 12 mo · Bracket: 22% · State: CA · Rates as of 2026-05-09
Principal
Savings figures are tax-equivalent ($) over the window above, vs. HYSA baseline.
HYSA (Marcus by Goldman Sachs)
No minimum balance, no fees, no DD required
Nominal
Effective (CA)
3.50%baseline4-week T-Bill
State-exempt · rolls every 4 weeks — yield assumes today's rate holds at each rollover
Nominal
Effective (CA)
4.74%+$11/mo · +$129 over 12mo13-week T-Bill
State-exempt · rolls every 13 weeks — yield assumes today's rate holds at each rollover
Nominal
Effective (CA)
4.74%+$11/mo · +$129 over 12mo26-week T-Bill
State-exempt · 6-month term
Nominal
Effective (CA)
4.85%+$12/mo · +$140 over 12mo52-week T-Bill
State-exempt · locked rate for the full 12-month term
Nominal
Effective (CA)
4.85%+$12/mo · +$140 over 12mo3-mo CD
Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end
Nominal
Effective (CA)
3.60%+$1/mo · +$10 over 12mo6-mo CD
Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end
Nominal
Effective (CA)
3.70%+$2/mo · +$21 over 12mo12-mo CD
Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end
Nominal
Effective (CA)
3.80%+$3/mo · +$31 over 12moI-Bond composite
Federal-deferred · 12mo lockup · 3mo penalty if redeemed before 5 yrs · variable rate resets May & Nov
Nominal
Effective (CA)
—window too shortCA Muni MMF
Federal + CA state exempt · 7-day yield can swing ±30bps week-to-week
Nominal
Effective (CA)
3.20%-$3/mo · -$31 over 12mo| Vehicle | Nominal· tap to edit | Effective (CA) |
|---|---|---|
HYSA (Marcus by Goldman Sachs) No minimum balance, no fees, no DD required | 3.50%baseline | |
4-week T-Bill State-exempt · rolls every 4 weeks — yield assumes today's rate holds at each rollover | 4.74%+$11/mo · +$129 over 12mo | |
13-week T-Bill State-exempt · rolls every 13 weeks — yield assumes today's rate holds at each rollover | 4.74%+$11/mo · +$129 over 12mo | |
26-week T-Bill State-exempt · 6-month term | 4.85%+$12/mo · +$140 over 12mo | |
52-week T-Bill State-exempt · locked rate for the full 12-month term | 4.85%+$12/mo · +$140 over 12mo | |
3-mo CD Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end | 3.60%+$1/mo · +$10 over 12mo | |
6-mo CD Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end | 3.70%+$2/mo · +$21 over 12mo | |
12-mo CD Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end | 3.80%+$3/mo · +$31 over 12mo | |
I-Bond composite Federal-deferred · 12mo lockup · 3mo penalty if redeemed before 5 yrs · variable rate resets May & Nov | —window too short | |
CA Muni MMF Federal + CA state exempt · 7-day yield can swing ±30bps week-to-week | 3.20%-$3/mo · -$31 over 12mo |
How $10,000 compounds over 12 months
Best at this window: T-Bill 26w at 4.85% effective.
T-Bill 26w wins because the CA state-tax exemption (9.30%) grosses up its 4.40% nominal yield to 4.85% effective — beats CD 12mo's 3.80% APY at your 22% bracket.
Common questions
What people Google before trusting a yield calculator.
How is after-tax yield calculated?
The tool converts each vehicle's nominal APY into a tax-equivalent yieldfor your bracket. A 5.00% HYSA at the 24% federal bracket is effectively a 3.80% after-tax yield (5% × (1 − 0.24)). T-Bills add the wrinkle that they're state-tax-exempt — so a 4.50% T-Bill in California at 9.3% state tax has the same after-tax value as a HYSA paying ~5.00% nominal.
The bracket is derived from your gross income minus the standard deduction. You can override it if you have significant itemized deductions, QBI, or other situations that put you in a different actual bracket.
Why are T-Bills state-tax-exempt?
Interest on U.S. Treasury obligations — T-Bills, T-Notes, T-Bonds, I-Bonds — is exempt from state and local income tax under federal statute (31 U.S.C. § 3124). Federal tax still applies. The exemption is what makes T-Bills competitive with HYSAs even when the nominal APY is slightly lower, particularly in high-state-tax states (CA, NY, OR, HI).
How long do 0% APR promos usually run?
Current market is 15 to 21 months on no-annual-fee cards. Wells Fargo Reflect and Citi Diamond Preferred sit at 21 months; Bank of America Customized Cash Rewards and Chase Slate Edge land around 18; Discover it Balance Transfer is typically 15. Anything shorter than 12 months is usually a deferred-interest store card — read the fine print first.
Deferred-interest vs. true 0% APR — what's the difference?
True 0% APR means no interest is charged during the promo window. If you carry a balance at the end, interest applies going forward from that date.
Deferred interest means the issuer is tracking interest the whole time. If you don't pay the full balance by the promo end, all that tracked interest is added retroactivelyback to day one. This is the financing pattern on most store cards (Apple, furniture, dental). Read the agreement — the words to look for are "deferred" or "same as cash." This tool models true 0% APR; deferred-interest cards are out of scope and are usually a trap.
Where do the rate updates come from?
T-Bill yields come from fiscaldata.treasury.gov, refreshed automatically. I-Bond rates come from the Treasury composite rate page. HYSA rates are manually verified weeklyfrom issuer pages — not pulled from an aggregator and not affiliate-driven. The "Rates last updated" stamp at the top of the page reflects the most recent successful refresh.