FIRE Essentials

The best way to predict the future is to create it. In 2016 Katie and I headed to Ecuador to go on Chautauqua, a financial independence retreat. We were desperately trying to work out how to invest and whether to invest in pensions or not. At the event we met the Mad Fientist who sat down with us and helped us to create our first ever financial model.

This gave us the confidence we could make it to Financial Freedom, which pots to invest in and helped us really get going on our journey. We have been developing that spreadsheet for the last 11 years and still come back to it every time we need to make big financial decisions.

🎯 What you’ll take away

• A personal 10–30 year forecast.
• A simple way to compare options side‑by‑side (A vs B vs C).
• The confidence to stress test your plan (inflation, market wobbles, big spends).
• A clear next action you can do this week.

⚙️ Get ready (2‑minute prep)

1. Download the spreadsheet
2. Open it before we start (laptop/desktop is best)
3. Have numbers handy: balances, spending, income, ages (SIPP/state pension), any big spends you’re dreaming about

🌳 The Decision Library (all the big choices you can model)

Summary: When you know your numbers, you make better decisions for you and your family – less worry, more freedom, sooner.

1. Retirement Timing & Bridge Planning
   • When can I retire?
   • Can I stop full‑time work at 52 and bridge to SIPP at 58?
   • Am I Coast‑FI yet (can I stop contributing and let compounding finish the job)?
     
2. Account Allocation (UK: ISA vs SIPP vs LISA, NZ: KiwiSaver vs Non-KiwiSaver)
   • What’s the right ISA:SIPP ratio for early retirement?
   • Should I chase SIPP tax relief or keep more in ISA for flexibility?
   • How do LISA/SIPP top‑ups change the picture?
   • You can also use the bridging calculator to make this decision.
     
3. Housing Decisions
   • Rent vs buy – what actually gets me to Financial Freedom faster?
   • Downsize and invest the equity?
   • Sell up and live nomadically (or buy a boat/campervan)?
   • The impact of buying that bigger 4 bed house on your financial future
     
4. Work & Lifestyle Choices
   • Can I go part‑time without blowing up my plan?
   • What if I switch careers or take a sabbatical?
   • What if I pause contributions and Coast‑FI?
     
5. Big Purchases & Life Events
   • Wedding, world trip, kitchen, campervan – what’s the real cost in years to FI?
   • What size “fun budget” can I afford without stressing future me?
     
6. Debt vs Investing
   • Pay off that 0% loan or invest instead?
   • Use pension lump sum to clear debt – smart or not?
   • Should I pay off the mortgage or invest – see the difference
     
7. DB Pension Decisions
   • Keep guaranteed income or take the lump sum and invest?
   • How does inflation protection, flexibility, and timing compare?
     
8. Windfalls & Inheritance
   • Best use of an inheritance or equity release?
   • Pay off mortgage vs invest – what wins over 10–20 years?
     
9. Stress testing & “What-ifs”
   • What if inflation skyrockets?
   • What if markets don’t grow as much as we expect?
     

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🌍 “I’m from ….. Will this work for me?”

Yes. Maths doesn’t care where you live. 🌎

• The model is jurisdiction‑agnostic. We exclude tax on purpose so you can compare options clearly.
• Plug in your local accounts (KiwiSaver, 401(k), RRSP, Super, etc.) and your own access ages.
• Use it to compare pathways; then handle local tax fine‑tuning if needed.

🧩 Live Demos We’ll Build Together (and you’ll copy with your numbers)

In the workshop we will do three live demos and show you how the spreadsheet works. You can then copy along and input your numbers tweaking for your situation. This will enable you to side by side compare different situations and see the impact over time on your financial wellbeing!

Who is running the workshop?

Katie is an excel and data nerd. She LOVES numbers, maths and creating charts and graphs of financial data. Katie did a degree in stats, qualified as an actuary and has spend the last few years modelling financial data.

These are the skills that enabled her to retire at 35 and volunteer her time to help other people get on top of their finances.

Alan loves financial independence, after meeting the Mad Fientist in Ecuador at Chautauqua he was inspired to work on a financial model that could predict his financial future and help work out if he and Katie would have enough to retire!

Having fixed his finances he now volunteers his time to run Rebel Finance School helping others to do the same.

Course Objective

By the end of this course you will have the skills to build your own financial model to predict your financial future.

Come with Excel open and build along as Alan and Katie guide you through creating your own spreadsheet live on the course.

You will learn how to use maths to make better financial decisions for you and your families future.

Course Pre-requisites​

• Excel skills – you know how to use formula, lay out a simple spreadsheet and can navigate excel. If this isn’t you don’t worry Katie created an entire Beginners Guide to Excel course to help you get up to speed or check out the Maths and Spreadsheets workshop Katie did for you.
• Basic Financial Freedom knowledge – we will not be covering index funds, 4% rule or other basic Financial independence principles in this workshop. If you want to get up to speed with that, first watch Rebel Finance School

Here is the spreadsheet template.  Download it here and then follow the instructions below the video on how to set it up ready for the workshop.

🧭 How to set up the spreadsheet (quick tour)

The spreadsheet takes a little bit of time to set up with all your numbers. Use the quick start guide below to understand the sections and where to add your numbers. Or just follow along in the workshop above and fill it out with us. Hit pause as many times as you need to update your figures.

A. Assumptions

• We work in real terms (today’s money) because the spreadsheet handles inflation for you. Enter everything in today’s figures – which is sooooo much simpler.
• Default assumes 100% equities. Prefer bonds? Reduce the growth assumption to reflect your mix.

Have no idea what either of these mean? Watch Rebel Finance School

B. Layout overview

The main Playground tab is where the action is. As you move around the playground tab you will see the following sections for you to update. Any cells in blue are for you to populate with your details and numbers.

• Year, names and ages → who are you and how old are you
• Investments in the stock market → where your pots sit and grow
• Income → job, DB pensions, state pension, rental, side hustles
• Spending → annual spend + lump sums (car, kitchen, boat, 50th…)
• How spending is covered → auto‑calculated (income first, then stocks)
• Contributions → what you add each year (incl. employer + tax relief)
• Gap / contributions check → sanity check you’re allocating the surplus
• Blue fields = you fill these in with your numbers

C. First choice: Solo or couple?

• Put your name in Person 1.
• Leave Person 2 blank or… leave space for the amazing human yet to arrive. 💛
• Input the current year and the rest of the sheet will update automatically

D. Populate investments in the stock market

• Use your net‑worth tracker to grab current balances.
• Rename columns so they match your accounts.
• Order by access: ISA/GIA first, then SIPP, then LISA, etc.
• Group similar (e.g., all workplace pensions/SIPPs together).
• Different Country: Kiwi example (KiwiSaver) and US example (401(k)/Roth). Same logic, different labels.
• The sheet auto‑adds totals, auto‑calculates withdrawal, and auto‑applies growth from Assumptions.

E. Income

• Job income: how much and how long (this is how you model part‑time/Coast‑FI assumptions)
• Use after‑tax best estimate numbers for income
• DB pensions: scroll to the start age and enter the annual amount.
• State pension: scroll to access age and pop it in (2025 UK ref: £230.25/wk; use your local equivalent eg. social security (USA) or superannuation (NZ/Aus).

F. Annual spending (guestimate is fine)

• Enter today’s numbers (inflation is allowed for! woo!)
• Add lump sums (birthdays, cars, home projects, sabbaticals).
• Want to roughly allow for tax in retirement? Pad the spending figure slightly.

G. How spending is covered (hands off – this runs itself)

• First from income, then from stocks if needed. Theses cells will all auto-populate and update for you. More details in the workshop.

H. Adding to investments

• The gap (income − spending) is what you can invest while building your freedom fund.
• Enter your and employer contributions; include tax relief.
• Check at the end: have you allocated your whole gap?

I. Gap / contributions check

• Flags if you still have surplus (or if you “overspent” contributions).
• It’s OK if it’s off for a reason – add a note (e.g., extra shows tax relief/employer boost).

J. Understand the drawdown logic

• The sheet spends income first, then from the first investments column (the most accessible bucket).
• Break it on purpose to see what happens (go negative) → quick lesson in runway!
• We keep it simple (it always draws from that first column). You just need to check that the sum of accessible columns stays positive.
• Spreadsheet whizzes: go wild and build cascading drawdowns if you want. 🧪

💬 FAQ (speed round)

Do I need advanced Excel?
Nope. If you break a formula, the Cheat Sheet tab has copy‑and‑paste repairs.

Does this replace the Rebel Finance School course?
It builds on it – this is the practical, “let’s do your numbers now” bit.

Will it work in my country?
Yes. Maths is universal. Plug your accounts and access ages into the same logic.

Can I watch later?
Yes. The replay stays on this page, embedded, forever‑ever.

🎬 Your next 3 clicks

1. Download the spreadsheet
2. Add your current balances & spending (blue cells at the top of the Playground tab)
3. Join live on Monday 18 August 2025, 8pm UK time (or hit play on the embedded replay)

Let’s stop guessing and start planning – together. Maths, spreadsheets and numbers are your biggest tool for building a bright financial future. Let’s take away the clouds, mystery and fear and replace that with clarity, insight and confidence in the future.

You’ve got this. Please let us know what you think. We are always updating, improving and working on the tools to help you get to financial freedom. Send us a message or share your insights as we love to learn too!

Peace and Pineapples.

Alan & Katie from Rebel Finance School 🍍

⚠️ Disclaimer

This spreadsheet is a simplified forecasting tool. It assumes straight-line average stock market growth and doesn’t fully account for Sequence of Returns Risk, tax, or market volatility. It’s not a prediction of what will actually happen in the future. We’re not financial advisors, and we’re not telling you what to do – this is a thinking tool to help you make your own informed decisions. If you make a big decision based on this and it doesn’t turn out how you’d hoped… we’re not liable! You’re the boss of your own financial life.

Read our full disclaimer here