What a large cash cushion earns if left in checking by default.
Moving a $16,000 cushion to a competitive savings rate instead.
The incentive runs the other way.
See Why the Nudge Never Comes
Charlie Munger's published emphasis on incentives argued that understanding who benefits from an arrangement explains behavior better than assuming good faith, and incentives behind why your bank wants your cash cushion in checking becomes clear once you recognize that an idle checking balance costs the bank nothing while still funding its own lending activity. For example, consider a household keeping a $16,000 cash cushion in a checking account earning 0% APY, believing the bank would eventually suggest a better home for it if one existed. After three years, no such suggestion ever came, while a comparable high-yield savings account at the same institution paid 4.2% APY the entire time, a gap of roughly $672 a year that persisted simply because moving the money required the household's own initiative. The Berkshire Hathaway letter archive documents Munger's repeated insistence that incentives, not stated intentions, predict behavior more reliably. As of July 2026, this is especially important if you're holding a meaningful cash cushion in checking while waiting for your bank to suggest a better option.
The bank has no incentive to prompt this move. The household has to initiate it.
Move It Yourself, Since the Prompt Won't Come
Per Poor Charlie's Almanack, understanding the reward structure behind an institution's behavior was treated as more useful than assuming its interests automatically align with a customer's. Comparing your checking balance's rate against the national average of 0.38% APY and the best available 4.20% APY, using FDIC national rate data, reveals the gap directly.
| Signal | What it usually means | Next check |
|---|---|---|
| Large checking balance, no bank prompt to move it | Normal, not a sign of anything specific | Move any genuine excess yourself |
| Balance well above monthly spending needs | Likely idle cash earning nothing | Read inversion applied to where you should not keep idle cash |
| Automatic sweep or savings-link feature available but unused | An easy fix once identified | Set it up directly with your bank |
| Cushion already moved to a competitive account | Aligned with your interest | Recheck the rate periodically |
Understanding this incentive gap has real benefits: it removes any false expectation that a bank will proactively move your idle cash to a better-paying account. The risk of waiting for that prompt, as the three-year example shows, is real, ongoing forgone interest with no external signal to catch it. However, that said, it depends on your actual checking balance compared to your genuine monthly spending needs: some buffer in checking is reasonable for timing flexibility, while a large, persistent excess is the specific pattern this incentive gap affects. If you're deciding whether to move your cash cushion, choose to move any balance meaningfully above your typical spending needs into a competitive account; choose to keep a reasonable buffer in checking only if you have a specific, recurring reason for it. This is when this matters most: any time a cash cushion has sat in checking for more than a few months without an active decision to keep it there.
An idle checking balance costs it nothing, so there's no incentive to suggest moving it.
Compare rates and act, rather than waiting for a suggestion.
Some checking cushion for timing flexibility is fine; a large excess isn't.
Once moved, confirm the new account's rate stays competitive too.
When This May Not Apply
A modest checking buffer kept intentionally for timing flexibility, bill timing, irregular income, isn't the same pattern as a large, persistent excess earning nothing by default. This is especially important to distinguish a deliberate buffer from simple inertia.
What to Do Next, in 20 Minutes
- Check your checking account balance against your typical monthly spending.
- Move any genuine excess to a competitive high-yield account.
- Read inversion applied to where you should not keep idle cash and why the boring account usually wins for related frameworks.
- Read the checking account guide for balance-management basics.
- Run a full Money Map check to see your full cash picture in one place.
Sources and Methodology
This article applies Charlie Munger's published incentives principle to household cash-cushion placement. It is educational and does not recommend any specific institution.
- Berkshire Hathaway letters· Checked 2026-07-10
- Poor Charlie's Almanack· Checked 2026-07-10
- FDIC National Rates and Rate Caps· Checked 2026-07-10
- SwitchWize methodology· Checked 2026-07-10
Next scheduled verification: 2026-10-10
Educational content from the SwitchWize Research Desk. Charlie Munger and related entities are not affiliated with or endorsing SwitchWize.
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Check whether my cushion is earning where it sits →Frequently asked questions
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Disclaimer
This article is educational and does not provide personalized investment, tax, legal, or financial advice. Charlie Munger, the Munger estate, Berkshire Hathaway, and related entities are not affiliated with or endorsing SwitchWize. References to public letters, speeches, and books are used for educational interpretation only.