Couples FI Planner

1. 1.Pool the money and the spending

   Shared assets and both partners' personal assets add up to one household portfolio. Shared expenses plus each partner's personal expenses give total spending, held flat in today's dollars.

   portfolio_0 = shared_assets + a_assets + b_assets
   expenses = shared_expenses + a_expenses + b_expenses

2. 2.Set a moving target

   Each year, subtract any pension that has started from total spending, then divide by your withdrawal target. A pension lowers the target in one step the year it begins.

   net_spend = max(0, expenses - pension_income)
   target = net_spend / withdrawal_target

3. 3.Roll the portfolio forward

   Each partner saves until their own retirement age. Once one retires, their personal costs come out of the portfolio, and shared costs follow when both have retired. The balance compounds at your real return.

   portfolio_next = (portfolio - withdrawal) x (1 + real_return) + contributions

4. 4.Find the FI year

   The FI year is the first year the portfolio meets that year's target, no later than the first partner's retirement. If it never does, the plan reads Off track. Milestones repeat the search at 5%, 4% and 3.5%.

1. The starting portfolio is $120,000 shared plus $430,000 and $370,000 personal, or $920,000. Spending is $28,000 shared plus $48,000 and $36,000 personal, or $112,000 a year. The 4% target is $2,800,000, so you start 32.9% funded.
2. Both partners save while working, $57,000 a year combined. That drops to $32,000 when Ethan retires at 55 and stops when Maya retires at 58.
3. At a 5% real return the portfolio first reaches the target 14 years out, when Maya is 50 and Ethan is 51. That is before either retires, so both checkpoints show a surplus: $1,815,361 for Maya and $1,017,636 for Ethan.
4. At a 5% withdrawal target the crossing comes 11 years out (Maya 47), and at 3.5% it comes 16 years out (Maya 52). Maya's pension starts at 60 and cuts the target from $2,800,000 to $2,200,000.

FI arrives in 14 years, ten years before Maya's $24,000 pension starts. The pension cuts the target by $600,000, but only from age 60, so this household has to be fully funded without it.

• One steady real return, with no volatility or sequence-of-returns risk. Spending stays flat in real terms and never steps down when kids leave or a mortgage ends.
• Pensions are treated as fully inflation-indexed from their start age, with no survivor reduction or early-claiming haircut. One that doesn't keep up with inflation is worth less than this assumes.
• Taxes and Social Security aren't modeled. Put expected taxes in your expenses, and enter a benefit as a pension with the age you plan to claim.
• Savings stop exactly at each retirement age, so part-time work needs an approximation: lower savings and raise the retirement age. Healthcare before Medicare isn't priced separately.
• The projection runs to age 95 for the younger partner, or 40 years if that is longer. These are estimates, not financial advice.

FI year

The first year the portfolio meets that year's target, no later than the first retirement, and how many years away it is. Never if it doesn't.

On track or off track

On track means you're funded by the first retirement. Off track means withdrawals start while the portfolio is short of target.

Timeline events

Each partner's retirement, any pension start and the household's FI crossing, each with its year.

Retirement checkpoints

Each partner's retirement year, the projected portfolio and target that year, and the surplus or shortfall between them.

Milestone ladder

The target portfolio, the share funded today and the crossing year at 5%, 4% and 3.5%: what a more conservative plan costs, in years.

Scenario comparison

Up to three scenarios side by side, each with its FI year and how far it moves from the base plan.