I have been reading many posts about SWR (Safe Withdrawal Rate) and while I think I understand the reasoning and the mechanics that produce retirement planners, it seems to me that the subject is more complicated in practice.
The generally accepted definition that most seem to adhere to, comes from Bogleheads:
A safe withdrawal rate is defined as the quantity of money, expressed as a percentage of the initial investment, which can be withdrawn per year for a given quantity of time, including adjustments for inflation, and not lead to portfolio failure; failure being defined as a 95% probability of depletion to zero at any time within the specified period.
Usage: Typically, SWR is utilized as an approximation of the probability that a given portfolio can support a given annual spending component for a required period, with a reasonable confidence. To do this, variables such as the allocation of assets within a model portfolio, the beginning balance, and/or the number of years expected in retirement are varied, a model is applied, and results of these alterations in the variables are observed and compared, in order to optimize for the maximum.
This is not to disagree, but to point out the difference between a 30 year period and a 5 year period... and the "depletion to zero" factor, and the 95% probability.
The SWR if I understand it correctly, applies to an investment portfolio, and not to (1.) net worth or (2.) Social Security.
(correct me if I'm wrong SS and if so, how to calculate SS for 30 years).
On net worth... Here, the question (for me, anyway) is: Why should I not calculate this? Since we are talking about "withdrawal"... let us take this as a case in point:
Portfolio of $1 million. Age 65, plan to age 90 (20 years)... SWR 4% = $50K/yr., in FireCalc, an 80% success rate.
Now, it is clear that this only deals with the portfolio. It leaves other variables to be decided by you.
.........
So, still dealing with what if's... what happens to your actual spending rate if you were to add $30K/yr in SS? (two people). Well, easy enough to figure.
$50K + $30K = $80K
But then, what about your the balance of your net worth? Since we're basically calculating if you can afford to live to that age 90... and not whether you'll be giving $300K to the SPCA...
This is where I see a difference. What about your home, or other properties, or other assets that could covert to cash? This is where my philosophy and experience differs from othere here on ER. I calculate the value of my home as part of my retirement plan. Sure it's nice to think you'll always live in your dream home, but 2500 s.f. is a lot of cleaning-walking - replacing - repairing-and cluttering. For us, 1000 s.f. apartment living in a retirement community is very desirable even now. So, let's say the house would bring another $250K. Over the 25 years, that's another $10K/yr for a total of $90K spending.
Now, you can say... "But you have to live somewhere!" In our plan, the total living costs in our CCRC, in an apartment, ... including healthcare, food and entertainment, is less than $40K. (See phase II planning)
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And so... to simplify, here's a plan... based on net worth.
Make believe numbers...
10 years to go.
Net Worth $500K divided by 10 years = $50,000/ yr
Social Security $25K yr.
That calculates to $75K/yr spending.
Doesn't include interest, dividends or inflation, and our chances of living to that age is around 35%.
We're in better shape than that, but a simple example that includes SS and
non portfolio assets.
Give it a try... simple.
Total net worth divided by number of planned retirement years plus annual Social Security or Pension $$$'s = Annual Spending.
Aw... don't take this too seriously... it's just an old man, trying to simplify the numbers.