Two personal allowances, two basic-rate bands, tax-free transfers between spouses — why the same household income can cost thousands less when drawn as a couple, and how Hundred Summers computes the split.
Most couples plan retirement as two individuals who happen to share a house — each drawing their own pension for their own spending. The tax system quietly punishes that: it gives every individual their own £12,570 personal allowance and their own basic-rate band, and it lets married couples and civil partners move money between each other tax-free without limit. Used together, those three rules are worth thousands a year to an unbalanced household.
A couple has £25,140 of tax-free income capacity every year and over £75,000 of basic-rate capacity. If one partner holds most of the pension wealth — the usual shape after one high-earning career — an uncoordinated plan draws heavily from that partner at 40% while the other's allowance and band sit idle. The coordinated alternative: draw the same household total, but source each pound from whichever partner pays least on it — fill both allowances, then both basic bands — and let the balancing cash move between you, which between spouses costs nothing.
Coordination can also rescue spending that two individual plans literally cannot fund: one partner running out of accessible money while the other holds plenty is a failed plan for the household even though the balance sheet looks fine. And the fixes compound upstream — pension contributions routed to the higher earner's relief while working, the marriage allowance when one income is low, assets rebalanced so both future incomes exist at all.
The Household tab's coordinated-drawdown what-if re-runs both partners' real plans with every shared retirement year's draw split cheapest-taxable-pound-first through the same per-person tax engine as every other number in the app. It reports three things separately, because they are honestly different: tax saved in like-for-like years, spending rescued that the uncoordinated plans couldn't fund, and the household net-worth difference at plan end. A pattern to understand, not advice — coordinating changes whose name the wealth sits in, and that has consequences (divorce, death, care means tests) beyond the tax arithmetic.