The 5.00% APY That Quietly Becomes 3.10%: How Teaser Savings Rates Decay

Olivia opened a 5.00% APY savings account in January, moved over $28,000, and felt smart. She did not read the asterisk. The 5.00% applied to balances up to $1,000 for the first three months. Everything above that, which was almost all of it, earned the ongoing rate, and after the promo lapsed the whole account drifted to 3.10%. She is still earning interest. She is also leaving real money on the table every month and has no idea, because the number on her statement never screamed. (Olivia is a composite; the rate mechanics are real and on the market right now.)

Quick answer

A teaser APY is only worth what it pays on your actual balance once you account for the balance cap, intro window, or hurdle behind the headline number. Find the ongoing rate before you move money, and re-shop every quarter — the bank has no reason to tell you when your rate quietly drops.

Here is the detonating fact. Today you can find a savings account advertising 10.00% APY and earn it only on your first $1,000, which caps the actual benefit at about $8 a month no matter how much you deposit. Above that cap, the same account pays a rate you could match at a dozen plain high-yield accounts. The headline is not a rate. It is bait shaped like a rate.

Three ways the number on the ad is not the number you earn

The balance cap. A handful of accounts pay eye-watering APYs, but only on a sliver of your money. At 10.00% on $1,000, you earn $100 a year, full stop. Put $30,000 in and the blended yield collapses toward whatever the above-cap tier pays. The big number is mathematically true and financially irrelevant.

The intro window. Many boosts are temporary. One major online bank runs a 0.10% rate boost for new accounts opened by a cutoff date, plus an extra boost that requires a few thousand dollars in fresh deposits every statement period. Stack them and the headline looks great, until the window closes and the rate steps back down. None of these renew quietly in your favor.

The hurdle. Some top rates require direct deposit, a linked checking account, or a minimum number of debit transactions. Miss the hurdle one month and you silently drop to the base tier.

In every version, the bank is counting on the same thing: you opened once and never re-shopped.

The decay is the product

A durable, no-strings high-yield savings account today pays around 4.20% APY, about $400 to $420 a year per $10,000. The FDIC national average savings rate is 0.38%, about $38 a year per $10,000. That spread is the entire opportunity, and the teaser game is designed to walk you quietly from the top of it toward the bottom. It is the same decay that turns a savings rate you opened on into a lower one you keep, dressed up with a flashier opening number.

SwitchWize's live rate feed exists precisely because the ongoing rate, not the headline, is the number that compounds. Here is what the top of the market pays right now with no cap and no expiring window attached:

Run your own balance through the teaser-vs-ongoing rate calculator, or scan the full list of current high-yield accounts before you assume your rate is still competitive.

Watch what the decay costs in dollars, not basis points.

Olivia's slide from a real 4.10% to a post-promo 3.10% on $28,000 is $280 a year gone, for doing nothing wrong except not re-reading the fine print. The worse case is starker: drift from a 4.10% account all the way to a legacy 0.38% account on $30,000 and you forfeit about $1,116 a year, every year, on money sitting at identical FDIC risk.

Two savers, same balance, same insurance, separated only by whether they re-shopped.

Why sharp people get caught

Opening a savings account feels like a decision you make once. Everything in the experience reinforces that. The rate was great on day one, the money is safe, and nothing about the statement flags a downgrade. So the people most likely to get decayed are the responsible ones, the savers who set it and forget it, exactly as they were taught. The bank's edge is not a trick in the moment of opening. It is your inertia in the eleven months after, the same pull behind the lazy money trap.

What to actually do

The rules, stacked

• The headline APY is a marketing number. The ongoing APY is your actual return.
• A rate with a cap is a rate on the capped amount. Read the ceiling, not the number above it.
• Every boost has an expiration. If you do not know the date, the bank does.
• Loyalty earns nothing here. The reward goes to whoever re-shops.

Sources

• Fortune, NerdWallet, and WalletHub high-yield savings roundups (June 2026): durable top accounts about 4.00%-4.21%, capped/promotional offers up to 10.00% on small balances
• FDIC National Rates and Rate Caps — national average savings 0.38%, June 2026

What to do next

Olivia is a composite character; rates are representative and current as of June 2026. Educational only, not individualized financial advice.