Take one flexible pension withdrawal and your annual allowance drops from £60,000 to £10,000 — permanently, with no carry-forward. What triggers the Money Purchase Annual Allowance, what doesn't, and who it ambushes.
The Money Purchase Annual Allowance is the pension system's least-forgiving rule: touch taxable pension income flexibly once, and your annual allowance for money-purchase contributions falls from £60,000 to £10,000 — for the rest of your life, with no carry-forward. It exists to block recycling (drawing pension cash and re-contributing it for a second round of relief), but it catches far more people than recyclers.
Triggers: taking any income from flexi-access drawdown; any UFPLS payment (its 75% taxable element counts); cashing a whole pot beyond the small-pot rules. Not triggers: taking only tax-free cash with the rest moved to drawdown and left untouched; buying a lifetime annuity; drawing a defined-benefit pension; cashing pots under £10,000 under the small-pots rule (up to three personal pots). The gap between the two lists is where planning lives: someone who needs a lump sum can often take PCLS alone and keep their full £60,000 allowance.
The classic casualty is the fifty-something who dips into a pension during a rough patch — redundancy, illness, a gap between jobs — then returns to work and wants to rebuild. Their salary would support £30,000 of contributions; the MPAA caps them (and their employer, in total) at £10,000 of money-purchase saving with relief. One withdrawal made in a hard month can cost six figures of late-career pension building. Providers must send a flag notice when you trigger it, and you must tell your other schemes within 91 days.
Hundred Summers models the MPAA in its projections, and the free lump sum calculator and UFPLS guide carry the warning at the decision points where it belongs. If there is any chance you'll want to contribute seriously again, the order of operations matters: tax-free cash first, taxable income only when the rebuilding years are behind you.