Calculating 25x Expenditure with multiple withdrawal dates.

[Ukwhat?]

I understand the reasoning behind the 25x expenditure for a 4% SWR but i'm not 100% clear on what happens with multiple dates for access to the money.

Let's assume I can retire or achieve FI in 10 years (apprx 40 yrs old)

At the minute I'm saving and investing money in two ways.

1. Private investments - I can withdraw from it whenever.
2. Through a workplace pension that I cannot access for another 25+ years (55yrs old).

Do I add up the total of both to calculate the 25x value?
What happens if 75% of the money is in the pension where I have no access to it for 15 years? Would I not run out in the 15 years from the 25%?

Should I ignore the pension money and earn 25x in the private investments? I receive workplace contributions (3%) to my pension and also tax savings. For example I can increase my contributions to reduce my tax rate from 40% to 20% and so it makes sense to put most of money that achieves the above in the pension, but then have no access to it for a long period of time.

I don't understand the best options or how to work this out. Any advice?

[dreams_and_discoveries]

It's spreadsheet time - you need to work out a plan that meets the 25 x expenses rule overall, and doesn't have you out of money before you can access your pension - which is also likely to be age 57 + now (10 years before state pension).

Depending on how many years you have to go, you might need to start altering your contributions to balance these out.

If you want to play it safe, you'll need more than 25 x to ensure you don't run out; alternatively if the markets fall you amy be happy to cut expenses/get a part time job. You should also be able to bridge the last year on credit if the money runs out as a back up plan, and pay off with tax free lump sum.

[redcedar]

Agree with DandD. Spreadsheet time.

You could create a few scenarios and see how you feel about the results. Now 50yr old you may feel differently about the results than 30 year old you, so you may want to hedge a bit and chose something that is a bit more conservative that what feels right to you now.

I would recommend at least four scenarios with extremes at both ends.

25x total portfolio, high risk of running out of non-pension money before age 55
Amount to sustain 4% withdrawal pre-pension with moderate risk of running out of money
Amount to sustain 4% withdrawal pre-pension with low risk of running out of money
25x non-pension money, lowest risk but longest time before FIRE

[Rocket]

I'd create a free personal capital account and use the Retirement Planner tab.  You can enter all your income events like pensions, social security etc, and you can then play with the dates and the amounts. It will run the simulations and give you a spread sheet showing all the details.   If you're uncomfortable with linking your accounts you can just create manual ones for all your investments. 

[forummm]

Spreadsheets are your friend. And also cFIREsim. You can enter pensions, social security, one-time expenses, part time jobs, etc. It will look at how those scenarios played out over prior historical time periods if you retired at each year.

[Ukwhat?]

Thanks. I'll take a look at all of the suggestions. Does anyone know where a spreadsheet template may exist?