For a couple, the riskiest tax event in the plan is often one nobody prices: the first death. The survivor scenario models it as a deterministic what-if at an age you choose, not a mortality prediction.
From the chosen age, four things change at once:
- The survivor files Single: the standard deduction and bracket widths roughly halve, so the same income lands in higher brackets. This is the widow's penalty.
- Social Security drops to the larger of the two benefits; the smaller one is lost.
- Spending drops to your survivor percentage. ~75% is the convention because fixed costs don't halve when the household does.
- The tax-deferred balance re-bases onto the survivor's own RMD schedule.
The survivor chart shows the squeeze year by year: income halves while the tax bill climbs, which is exactly why couples often convert to Roth while both are alive and filing jointly. The same conversion costs materially more tax once the survivor files Single.
Deliberately deterministic: you pick the age and see the consequences, rather than averaging over mortality tables where the penalty would blur into the fan. Try a few ages; the shape of the answer is the point.