Glossary
Bank Gap Index, Loyalty Tax, Inertia Tax — what do they actually mean?
SwitchWize uses a handful of related terms across the site. They sound alike, and a few even share a formula, but each answers a different question. Here is every one, in plain language, with a simple example.
The gap family — same formula, different scope
All three answer "how much am I giving up by not switching?" — they just point the formula at a different population: the whole country, a different account type, or you specifically.
Bank Gap Index
A national, live-updating number: the spread between the best available high-yield savings rate and the national average rate, priced on a fixed $25,000 balance so it is comparable month to month.
Example
Say the best savings account pays 4.50% APY and the national average pays 0.40% APY — a 4.10-point gap. On the $25,000 benchmark balance, that is about $1,025 a year the typical saver is leaving on the table.
Bank Gap Index = (best available APY − national average APY) × $25,000
See today's live number →CD, Money Market & Checking Gap Indices
The same idea as the Bank Gap Index, rebuilt for other account types. A 12-month CD, a money market account, and a checking account each get their own tracked national spread between a typical account and the best available one.
Example
Say a typical 12-month CD pays 1.80% APY and the best available CD pays 4.30% APY. On $25,000, the CD Gap Index works out to roughly $625 a year.
Same shape as the Bank Gap Index, applied per account type
Browse all indices →Loyalty Tax
The personal version of the Bank Gap Index. Instead of the national average, you enter your own balance and your own current rate, so the dollar figure is yours, not a national estimate.
Example
Say you keep $40,000 in a savings account paying 0.30% APY, and the best available rate is 4.50% APY. Your Loyalty Tax is $40,000 × (4.50% − 0.30%) ≈ $1,680 a year.
Loyalty Tax = (best available rate − your rate) × your balance
Calculate your own →Different questions entirely
These two are not gap calculators — one is a broader vocabulary term, the other flips the question around.
Inertia Tax
An umbrella term, not a single calculator. It is the total cost of leaving anything un-optimized — savings, CDs, a mortgage, a credit card carrying a balance, avoidable account fees — added together. The Bank Gap Index and Loyalty Tax measure one slice of it (savings); the Inertia Tax is the whole picture.
Example
Say your Loyalty Tax on savings is $1,680/year, you are overpaying about $340/year in avoidable credit card interest, and you pay $15/month in account fees you could avoid ($180/year). Your total Inertia Tax is roughly $2,200/year.
Recovery Velocity
Instead of asking "how much am I losing," this asks "how fast do I get it back if I switch" — the dollars per month you would recoup, and how quickly that offsets the minor effort of moving your money.
Example
Say switching a $25,000 balance from 0.40% to 4.50% recovers about $85 a month. If opening the new account takes 20 minutes, you are already ahead by the time your first paycheck lands.
Recovery Velocity = (best rate − current rate) × balance ÷ 12
See how it works →Personal scores, not dollar figures
These two don’t output a dollar amount at all — they summarize your situation into a single number so you know where to focus.
Cash Efficiency Score
A personal, multi-account score from 300 to 850 — like a credit score, but for how well your money is working for you. It combines savings yield you are missing, credit card rewards left unclaimed, and account fees you are paying.
Example
Someone earning a top savings rate, using a strong rewards card, and paying no account fees scores near 850. Someone stuck at 0.30% APY, a no-rewards card, and $15/month in fees scores well below that.
Score = 850 − (yield loss + rewards loss + fee penalty), floored at 300
Get your score →Switch Score
Not a dollar figure — a quiz-driven match. Five quick questions about your accounts and goals produce a ranked list of which product category (savings, CDs, mortgage, credit cards) is most worth your attention right now.
Example
Answer 5 questions and get a result like: "Savings — high priority, Credit cards — low priority" tailored to your situation.
Frequently asked questions
What is the difference between the Bank Gap Index and my Loyalty Tax?
The Bank Gap Index is a national number — the spread between the best available rate and the national average, priced on a fixed $25,000 balance. Loyalty Tax is the same formula run on your own balance and your own current rate, so it shows what you personally are losing, not a national estimate.
If the Inertia Tax has no calculator, how do I find my own number?
Add up the individual pieces: your Loyalty Tax on savings, any overpaid credit-card interest, an un-refinanced mortgage, and avoidable account fees. Money Map estimates all of these at once in about 90 seconds.
Why does SwitchWize use so many similar-sounding terms?
Each one answers a slightly different question: how big is the national gap (Bank Gap Index and its category siblings), how big is it for you specifically (Loyalty Tax), how broad is the total picture (Inertia Tax), how fast do you recover it (Recovery Velocity), and how well is your whole setup performing (Cash Efficiency Score, Switch Score). This page exists so the family is easy to tell apart.
What is the "Competitive Gap Index"?
You may see this phrase in SwitchWize research notes or data pages. It is an internal SEO benchmarking metric used to compare our content coverage against competitor sites — it has nothing to do with your money and is not a tool you will interact with directly. The name overlap with "Bank Gap Index" is coincidental.
Reviewed by SwitchWize Research Desk · July 2, 2026. Examples above use illustrative numbers to show how each formula works — for live figures, see the linked page for each term.
Not sure where to start?
Money Map checks your savings, mortgage, cards, and debt against all of this at once and adds up what inertia is actually costing you.
Run Money Map →