The Retirement Income Gap: How to Find Yours (and Close It)

Your retirement income gap is the monthly shortfall between your guaranteed income (Social Security, a pension, annuity payments) and your essential expenses. To find it, add up income you cannot outlive, add up the bills you must pay, and subtract. A positive gap means guaranteed money runs short each month and you have to close it.

Anyone who has ridden the London Underground has heard the recorded voice say “mind the gap.” It is the space between the train and the platform, the little stretch of empty air you have to step across every time the doors open. Retirement has a gap just like it. On one side is the platform: the income that arrives every month whether the stock market is up, down, or on fire. On the other side is the train you need to catch, your actual monthly bills. For most people those two edges do not line up. There is a space in between, and you have to cross it every single month for the rest of your life.

Here is the quietly unsettling part. Almost nobody measures the gap before they retire. They know their 401(k) balance to the dollar. They could not tell you, within five hundred dollars, how much guaranteed income they will actually have coming in the month after their paycheck stops. That is like knowing the size of your gas tank but not your car’s mileage. The number that matters is the one nobody calculates.

This guide walks you through the subtraction, one step at a time. You will inventory your guaranteed income, inventory your essential expenses, find your gap, and then look at the honest menu of ways to close it. No hype, no scare tactics, just arithmetic you can do at your kitchen table.

What is the retirement income gap?

The retirement income gap is the difference between the income you are guaranteed to receive each month and the essential expenses you have to pay each month. It is a subtraction problem, not a mystery.

The reason the word “guaranteed” matters so much is that this is the money you can count on when everything else is uncertain. A stock portfolio can fall twenty percent the year you retire. Social Security keeps arriving. A pension keeps arriving. Annuity income keeps arriving. When we measure the gap, we deliberately leave volatile assets out of the “income” side, because the whole point is to see how much of your baseline life is covered by money that does not flinch.

Why do most people never do the subtraction?

Most people never calculate their income gap because saving and spending use two different mental muscles, and nobody teaches the second one. For thirty or forty years, retirement planning means one thing: build the pile. Contribute, match, compound, watch the number grow. Then you retire and the job silently flips. Now you have to turn a pile into a paycheck, and a pile does not come with a paycheck setting. The balance that felt enormous last week has to somehow produce reliable income for a retirement that could last thirty years.

The subtraction gets skipped for three ordinary reasons:

• Guaranteed income is scattered and hard to add up. Your Social Security estimate is on one website, your pension figure is in a benefits packet, and any annuity income lives in a contract. Nobody hands you the total.
• “Essential” and “nice to have” blur together. Until you separate them, you cannot tell how much of your spending is truly non-negotiable, and the gap only matters against the non-negotiable part.
• The pile feels like the answer. A large 401(k) balance is reassuring, so people assume it settles the question. It does not, because a balance is not a rate of safe monthly income, as the section on portfolio withdrawals below makes painfully clear.

Doing the subtraction takes about twenty minutes. The rest of this guide is those twenty minutes.

How do you find your gap?

Two inventories and one subtraction, in that order.

What counts as guaranteed income.

Add these up. That total is your guaranteed monthly income, the platform you are standing on.

What counts as an essential expense.

• Housing. Mortgage or rent, property taxes, homeowners insurance, HOA dues.
• Food. Groceries, not restaurants.
• Healthcare. Medicare premiums, supplemental coverage, prescriptions, expected out-of-pocket costs.
• Utilities. Electricity, gas, water, phone, and the internet you now genuinely need.
• Transportation. Car payment, fuel, insurance, maintenance, or transit costs.
• Insurance and taxes. Any remaining life or auto premiums, plus income taxes you will still owe.

Everything else (travel, dining out, hobbies, gifts, the boat) goes on a separate discretionary list. Discretionary spending matters enormously for your quality of life, but it is not part of the gap calculation, because in a hard year you can dial it down. The gap is about the spending you cannot dial down. Keep the two lists separate and the math stays honest.

The retirement income gap worksheet

Copy the two tables below onto paper or into a spreadsheet and fill in your own numbers. The whole calculation is three lines of arithmetic.

Table A: Guaranteed monthly income

Table B: Essential monthly expenses

Write that number down. It is the single most useful figure in your entire retirement plan.

How big a gap is actually a problem?

A gap is a problem in proportion to its size relative to your savings, not as a raw dollar figure. A 300-dollar monthly gap and a 3,000-dollar monthly gap are completely different situations, and the way to gauge yours is to translate it into an annual number and compare it to your nest egg. Multiply your monthly gap by 12 to get the yearly shortfall your savings has to cover.

Here is why that comparison matters. A widely cited benchmark for how much you can safely pull from an investment portfolio each year is the “4 percent rule,” a guideline the financial planner William Bengen introduced in the Journal of Financial Planning in 1994. It suggests a retiree can withdraw roughly 4 percent of a portfolio in the first year, then adjust for inflation, with a strong chance the money lasts about 30 years. More recent work has pushed the number in both directions: Morningstar’s retirement-income research, published in December 2025, estimated a safe starting withdrawal rate closer to 3.9 percent for someone retiring in 2026. These are third-party research guidelines, not a promise of any outcome.

What are the honest ways to close the gap?

There are really only five levers, and every one of them costs something. Anyone who tells you there is a free option is selling. Here is the honest menu, trade-offs attached.

Most solid plans use two or three of these levers together, not one. Delaying Social Security a couple of years, trimming spending a little, and covering the remaining gap with guaranteed income is a common, sane combination.

Where do guaranteed income products fit?

A guaranteed income product fits when you have a gap you want covered for life and you value certainty over flexibility for that slice of your money. An income annuity, sometimes called an immediate or deferred income annuity, takes a lump sum from your savings and turns it into a monthly payment that continues for as long as you live. In effect, you are buying yourself the pension your employer never gave you, aimed precisely at the gap number from your worksheet.

That certainty is genuinely valuable, and it is honest to name what you give up to get it:

• Liquidity. The money you commit to lifetime income is generally no longer a lump sum you can tap freely. You are trading access for a paycheck, so this should only ever be money you do not need on hand for emergencies.
• Inflation. A level payment does not automatically rise with prices. Some contracts offer a cost-of-living increase, but it usually lowers the starting payment to pay for itself. Read that trade-off carefully.
• It is not FDIC insured. An annuity’s payments rest on the claims-paying ability of the issuing insurance company, not on a bank or the federal government. Checking the carrier’s independent financial-strength rating, such as AM Best, is the closest thing to a self-service safety check.
• It is a decision that is hard to reverse. Committing to lifetime income is meant to be permanent. That is a feature when it is the right fit and a mistake when it is not, which is exactly why the sizing should come first.

One tool worth knowing about for the later years of retirement is a QLAC, a qualified longevity annuity contract, which uses a portion of retirement-account money to fund income that starts at an advanced age like 80 or 85. It is a way to insure specifically against the risk of living a very long time. Our QLAC overview explains how it works and its current contribution limits, and the broader retirement income annuity page covers the full menu of lifetime-income options.

Moving forward

Come back to the Underground for a second. “Mind the gap” is not a warning to be afraid of the train. It is a reminder to look down, see the space clearly, and step across it on purpose instead of tripping into it. Your retirement income gap works the same way. It is not a reason for panic. It is a number, and a number you can plan around is far less frightening than a vague worry you never put on paper.

You have the worksheet now. Fill in your guaranteed income, fill in your essential expenses, and find your gap. Then look at the five levers and decide which combination fits your life. If part of the answer is guaranteed income, size it first with our annuity payout calculator, then have a real conversation before you commit a dime. AnnuaLife matches you with a Certified Annuity Advisor whose job is to run your actual numbers and show you every lever, not just the one that pays them. That is advice, not a sales pitch, and it is the right way to cross a gap on purpose.

Frequently asked questions