The 80 Percent Rule for Retirement Explained and Improved

In How Much Money Do You Need to Retire, I mentioned using the 80% rule to calculate retirement needs. You may have heard this rule before; here is a variation of it:

You need 80% of your pre-retirement income during your retirement.

Where Did the 80% Number Come From?

The theory behind the 80% number is that there are things that will cost more during retirement and things that will cost less. Luckily, more things cost less.

What Costs Less

The 80 Percent Rule assumes several things happen by the time you hit retirement

• You would’ve paid off your home mortgage. If not, inflation would’ve made the payments feel much smaller.
• You would be done paying for your children’s expenses.
• You will be in a lower income tax bracket.
• Because you no longer commute to work:
  • You will spend less eating out — i.e., breakfasts and lunches.
  • You will spend less on transportation.
  • You will spend less on clothes and dry cleaning costs.

What Costs More

• You will pay more on home maintenance costs, insurance, and property taxes throughout your retirement.
• You will pay more for car insurance.
• Your utility bills may increase if you stay at home more
• Medical expenses will go up.

Once you take all these factors into account, the assumption is that you will need roughly 80% of your current income to maintain your current lifestyle.

Make The 80 Percent Rule Better

Now, 80% is just a rule of thumb and is not precise. Let’s make some improvements to the rule:

Use Expenses Not Income

Using current income is not a good predictor of your financial needs.

Some people make more than they need. For instance, I doubt Bill Gates needs 80% of his gazillion dollars income to retire comfortably. Conversely, some people spend more than they earn — in fact, a lot of us are in this category.

How much you need for retirement should depend on your expected expenses, not your current income.

Accounting for Taxes

Be sure to include your taxes as part of your expenses.

Unfortunately, income taxes do not disappear when you retire. If your only source of income is Social Security, you’ll most likely avoid income tax altogether. However, if you have other sources of income, e.g., rental income or pension, you’ll have to pay federal, and possibly state income taxes. Withdrawal from traditional IRA and 401(k) are also taxable at your ordinary tax rates.

Depending on your income level and the state you’re in, you are probably looking at around 10-20% effective tax rate. To be conservative, let’s assume 20%.

Revised Rule

Based on the two factors above and assuming the 80% holds true, your new rule becomes:

You need 80% of your pre-retirement expenses during your retirement.

For example, if you are currently spending $50,000 a year to live comfortably, you’ll need about $40,000 in income.

The Your Percent Rule

Unfortunately, even the improved version is still very imprecise. The 80% Rule has no idea what your budget looks like and what you plan to do during retirement.

To improve this further, you can figure out a more accurate percentage based on your budget. If you don’t have a budget yet, here is how to start a budget.

For example, let’s say your budget looks something like this:

The green categories will probably go down substantially, and the gray categories could disappear altogether. Let’s assume:

• Mortgage goes down to 5% because you paid off the mortgage and only have to pay property tax, homeowner’s insurance, and HOA fee. (-20%)
• Taxes could go down (let’s assume it go down to 15%) if you earn less or move to a state with a lower income tax. Also, not all of your Social Security income is taxable. (-5%)
• Groceries will probably go down when the kids leave. Let’s assume it go down to 5% (-2%)
• Your contribution for Retirement Savings and Child-Related expenses will most likely go down to 0% (-15% and -12%)

Based on these assumptions, your net expenses go down by 54% (i.e., 20% + 5% + 2% + 15% + 12%) to 48% of your current expenses.

Now, some other categories will probably go up, e.g., medical, travel, activities, etc. Retirees usually want to live out their dreams — e.g., travel to different countries, buy a little cabin in the woods, get a nice car, etc. This means that your post-retirement expenses could be higher in these categories. Let’s assume +25%.

At this point, we are at about 73% of net expenses. The good news is our example already include income taxes. As you can see, it is possible to maintain a decent lifestyle below 80%, assuming you’re debt-free.

The point is, if you have a budget, you can figure out a more accurate percentage of your current expenses you’ll need to cover during retirement.

Accounting for Inflation

One thing that is not covered well is the impact of inflation. All the calculations we have done so far are in today’s dollars. You need to figure out what you need when you’re ready to retire.

Using the Rule of 72 and 3% average inflation rate, your costs of living will double about every 24 years.

To be more precise, you can use an investing calculator (e.g., like this one at Calculator.net). Let’s see how inflation affects a $40,000 income requirement:

• 10 years from now you’d need about $54,000
• 20 years from now you’d need about $72,000
• 30 years from now you’d need about $97,000

Also, most Americans retire around the age of 65 and are expected to live to about 80 years old. That is 15 more years of inflation you will have to account for.

Bottom Line

The 80% Rule is a good start to help you think about your retirement income requirement. However, you can do a much better job of figuring out the percentage if you carefully evaluate your budget and decide what you will need, or not need, in the future. And be sure to account for inflation as you do your calculations.

You may need more than 80%, or you may need a lot less, but now you know how much you will need and that is the first step to figuring out how much you need to save so that your retirement savings can produce the right amount income to cover your expenses.

Pinyo Bhulipongsanon

Pinyo Bhulipongsanon is the owner of Moolanomy Personal Finance and a Realtor® licensed in Virginia and Maryland. Over the past 20 years, Pinyo has enjoyed a diverse career as an investor, entrepreneur, business executive, educator, financial literacy author, and Realtor®.