What is persistent absence?
A pupil is persistently absent when they miss 10% or more of the sessions they could have attended. In England that is the line at 90% attendance.
What 10% actually costs
Ninety per cent sounds like a good score, which is precisely the problem with it. Across a 190-day school year:
| Attendance | Days missed | Roughly |
|---|---|---|
| 95% | 9.5 | two school weeks |
| 90% | 19 | four school weeks |
| 85% | 28.5 | six school weeks |
| 80% | 38 | eight school weeks |
Four weeks is most of a half-term. Said as a percentage it sounds like a rounding error; said in weeks it sounds like what it is.
Why the threshold is 90% and not something else
It is a deliberately low bar, set to catch a group rather than to praise one. The point is not that 90% is acceptable — it is that below 90%, missed teaching reliably starts showing up in outcomes, so it is the line worth acting on rather than noting.
Authorised absence counts toward it
All of it. A child off sick for four weeks with notes for every day is persistently absent, in exactly the same way as one who was off without explanation. The measure is about teaching missed, not about blame — which is why it includes absence nobody could have prevented.
That often feels unfair to a family dealing with genuine illness, and it is worth saying plainly rather than letting it land as an accusation. See authorised vs unauthorised absence for what the distinction does change.
🔴 It is measured over a term, not over a week
A percentage needs enough sessions behind it before it means anything. One missed session out of one is nought per cent — nobody would call that pupil persistently absent, and the figure is not wrong so much as premature.
The arithmetic: before a single absence can put someone below 90%, there have to be at least ten sessions — one in ten is exactly 90%, which is not below it. Fewer than that and you are reading noise.
Early in a term, a run of consecutive absences is far more informative than the percentage. Three in a row is a pattern; three scattered across a year is a winter.
What happens when a pupil crosses the line
Nothing automatic. It is a flag for attention, not a penalty: schools are expected to notice, to understand why, and to put support in place. Formal steps — attendance contracts, penalty notices, legal action — follow from unauthorised absence and a lack of engagement, not from the 10% figure by itself.
Severe absence
A second threshold exists for pupils missing 50% or more of sessions, usually called severe absence. It is a much smaller group and a much harder problem, and it is tracked separately precisely because averaging it into the persistent figure hides it.
⚠️ General guidance for England, not legal advice. Thresholds and the way they are acted on differ in Scotland, Wales and Northern Ireland, and your school’s attendance policy is what applies to you.