Promo Float

Make idle cash work harder during a 0% APR window. Free, no signup, no affiliate links.

HYSA & card terms hand-verified · 2026-07-28

Where these come from

  • · T-Bill yields live from FRED (Federal Reserve H.15) on every page load.
  • · HYSA rates & card terms hand-verified from issuer pages · last pass 2026-07-28 — not affiliate-driven. The stamp above tells you exactly how old they are.
  • · I-Bond rate from the Treasury composite rate page (resets May 1 & Nov 1).

What you walk away with

You keep typically $650–$850 after tax by parking $20k in the best-yield vehicle during a 15-month 0% APR window — vs. leaving it in checking at 0.10%.

Best fit if

  • · You have $20k+ in cash sitting in checking/savings
  • · You have a $5k+ bill in the next 12 months — or just want to park cash during a 0% window
  • · You're comfortable opening a new credit card (670+ score helps)
  • · You want to capture the gap between your 0% promo and a high-yield account ($650+ after tax for most users)

Smaller scale? The math still works — the dollar number just scales down.

How it works

  1. 1Add a 0% APR card and how long the promo runs
  2. 2Add where your cash currently sits
  3. 3See the gap and where to close it

Realistic scenario: $20k balance, 15-mo promo, $22k cash, $5k bill.

Or jump to your situation:

I have a 0% card — park my cash →I have a bill to route →My promo is ending soon →No 0% card? Just see where to park cash →

Currently on offer: Wells Fargo, Citi, Bank of America, U.S. Bank, and Chase all run 0% APR cards with 15–21 month windows and no annual fee. Verified 2026-07-28.

What we calculate: highest after-tax yield · breakeven · transfer chains.

What we hand you: calendar alerts · penalty-APR flags.

New to float? See how it works →

Floatis the gap between when you owe money (a bill, a card balance) and when you actually have to pay it. A 0% APR card extends that gap by months — letting you park the cash you'd have spent in a yield account and earn interest on it risk-free. This tool finds the highest after-tax yield for your specific 0% windows, tells you the best account to open, and warns you about the mistakes that erase the win.

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

Purchase terms

Purchase APR applies from day one — no introductory window.

Balance transfer terms

No 0% balance-transfer promo on this card.

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 2026-07-28

Wells Fargo Reflect

personal

Wells Fargo

Purchase promo

21 mo

BT promo

21 mo · 5% fee

Annual fee

None

Credit score

670+

Longest purchase promo on the market. Flat 5% BT fee (min $5); transfers must post within 120 days to get the promo APR. Requires on-time payments to keep the full 21 months.

View offer →

U.S. Bank Shield Visa

personal

U.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 (transfers must be made within 60 days), flat 5% BT fee (min $5), $20/yr statement credit for 11 consecutive months of purchases.

View offer →

BankAmericard

personal

Bank 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 2026-07-28

Principal

Savings figures are after-tax dollars over the window above, vs. HYSA baseline.

HYSA (Marcus by Goldman Sachs)

No minimum balance, no fees, no DD required

Nominal

Effective (CA)

3.40%baseline

4-week T-Bill

State-exempt · rolls every 4 weeks — yield assumes today's rate holds at each rollover

Nominal

Effective (CA)

4.28%+$5/mo · +$60 over 12mo

13-week T-Bill

State-exempt · rolls every 13 weeks — yield assumes today's rate holds at each rollover

Nominal

Effective (CA)

4.43%+$6/mo · +$71 over 12mo

26-week T-Bill

State-exempt · 6-month term

Nominal

Effective (CA)

4.59%+$7/mo · +$82 over 12mo

52-week T-Bill

State-exempt · locked rate for the full 12-month term

Nominal

Effective (CA)

4.73%+$8/mo · +$92 over 12mo

3-mo CD

Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end

Nominal

Effective (CA)

—no verified offering — edit to add one

6-mo CD

Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end

Nominal

Effective (CA)

3.90%+$3/mo · +$34 over 12mo

12-mo CD

Illiquid — early withdrawal penalty applies; confirm you won't need funds before term end

Nominal

Effective (CA)

3.90%+$3/mo · +$34 over 12mo

I-Bond composite

Federal-deferred · 12mo lockup · 3mo penalty if redeemed before 5 yrs · variable rate resets May & Nov

Nominal

Effective (CA)

—window too short

CA Muni MMF

Federal + CA state exempt · 7-day yield can swing ±30bps week-to-week

Nominal

Effective (CA)

3.41%$0/mo · $0 over 12mo

Informational estimate, not financial or tax advice. APYs change without notice — verify with the issuer before opening an account.

How $10,000 compounds over 12 months

T-Bill 52w$10,325T-Bill 26w$10,315T-Bill 13w$10,304
0 mo12 mo

Best at this window: T-Bill 52w at 4.73% effective.

T-Bill 52w wins because the CA state-tax exemption (9.30%) grosses up its 4.17% nominal yield to 4.73% effective — beats CD 6mo's 3.90% 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 FRED (Federal Reserve H.15), fetched live on every page load. I-Bond rates come from the Treasury composite rate page, which resets each May 1 and November 1. HYSA rates and card terms are hand-verified from issuer pages— not pulled from an aggregator and not affiliate-driven — and the header stamp shows exactly when that last happened. If the stamp is more than 30 days old, the page tells you so instead of pretending otherwise; you can also edit any rate inline to match what you see on an issuer's page today.

How is this calculated?

After-tax yield. Each vehicle's nominal APY is reduced to what you keep after federal and state tax, using your bracket (derived from gross income minus the standard deduction, override available) and each vehicle's exemption profile — T-Bills are federally taxable but state-exempt, so high-state-tax users (CA, NY, OR) get a different ranking than zero-state-tax users (TX, FL, WA). The "effective" percentage shown in the comparison table is the tax-equivalent yield: the fully-taxable rate that would tie the vehicle after tax. Vehicles are ranked by after-tax yield; dollar figures are projected at after-tax yield too.

Float advantage. The headline figure is the after-tax interest your parked cash earns in the recommended vehicle over the promo window — a lump sum if your liquid cash covers the card balance, otherwise monthly set-asides. Compounded monthly from the APY, no fees assumed. It does not subtract what your cash currently earns — if your money already sits in a HYSA rather than checking, your incremental gain is smaller than this number.

Rate sources. T-Bills live via FRED (Federal Reserve H.15). I-Bonds via the Treasury composite rate page. HYSA rates and card terms hand-verified from issuer pages — not affiliate-driven. The header shows when each source was last refreshed or verified.

What we do not model. Penalty APR if you miss a minimum payment, deferred-interest store cards (always a trap — read the fine print before transferring there), or credit-score impact of opening / closing cards. The Risk section flags the first; the others are out of scope for now.

Informational tool, not financial, tax, or credit advice. APYs and promo terms change without notice — verify with the issuer before opening an account or transferring a balance. Tax math is a simplified estimate based on marginal brackets; consult a professional for your situation.

Personal-use tool. Cookieless analytics via Vercel. No auth; all data saved locally to your browser.

Why no affiliate links?
Most rate-comparison sites get paid when you open an account through them, which biases which "best HYSA" they recommend. This tool ranks vehicles by your actual tax-equivalent yield, not by who pays the highest commission. If a better account exists than what is listed, the list is wrong and I want to know.

Built by Gerardine Montebon — I had cash sitting in checking earning 0.10%, so I built this to figure out where to park it during my own 0% APR window. No accounts to create, no email collected. Just the math.

Live preview

Float advantage: $0