The things schools ask most often about attendance, answered properly. These are the DfE definitions with the official sources linked, plus the boundary cases that are easy to get wrong by hand. Nothing here is held back for a sales call.
What counts as persistent absence?90%
A pupil is persistently absent if they miss 10% or more of their possible sessions. That is attendance at or below 90%. A session is half a day. So in a school year of about 380 sessions, the line sits at about 38 missed sessions, or 19 days. It counts per enrolment, not per child. A pupil who moves school partway through the year is counted for the sessions they were on each roll. The boundary is the trap. Exactly 90.0% is persistently absent, not just outside it. A system that rounds the percentage before comparing will quietly miss those pupils.
What counts as severe absence?50%
Missing 50% or more of possible sessions, so attendance at or below 50%. Severely absent pupils are persistently absent too, by definition, so they appear in both counts. The number is usually small, and it is the one that matters most. These are the children missing half their education. They need a different response from a pupil drifting at 88%.
How is school attendance percentage calculated?sessions
Present sessions divided by possible sessions. A session is half a day, and approved off-site educational activity counts as present. Overall absence is 100 minus that. The whole-school figure is the part that catches people out. It is session weighted: you add up every session across every enrolment, then divide once. It is not the average of your year group percentages. Those two differ whenever year groups differ in size, and only the first matches what the DfE publishes.
When does a school have to consider a penalty notice?10 in 10
The National Framework threshold is 10 sessions of unauthorised absence in a rolling 10 school week period. Ten sessions is five school days. They do not have to be in a row. Two things are easy to get wrong by hand. The first is that the window rolls. It is not a term or a half term, so a pupil can cross the line, drop back under it, and cross again. The second is holidays. Weeks with no sessions should not dilute the window. Doing this by hand for a whole school is where it usually slips. Every pupil has to be re-counted every week.
What is the difference between authorised and unauthorised absence?Both
Authorised absence is absence the school has agreed to, such as illness or a medical appointment. Unauthorised absence is absence it has not agreed to. That includes a holiday taken in term time without leave. Both count the same towards attendance, and towards persistent absence. That surprises families: authorising an absence does not make it disappear from a child's attendance figure. Only unauthorised absence counts towards the penalty notice threshold.
Does authorising an absence improve a pupil's attendance figure?No
No. Authorised and unauthorised absence are both absence. Both reduce attendance by exactly the same amount. The difference changes what enforcement is available, not what the percentage says. Say that plainly to families. A parent told an absence was authorised often believes it has been discounted.
How often should a school monitor attendance?Weekly
Weekly is the pattern that changes outcomes. The point of monitoring is the conversation you have next week, not the figure you report next term. A pupil drifting towards 90% is reachable. A pupil who arrived at 84% over a term usually is not. By then the arithmetic is against you. Getting from 88% back above 90% part way through a year can take near-perfect attendance for the rest of it. So noticing early matters more than measuring precisely.
What does Ofsted look at for attendance?vs national
Ofsted's framework asks whether attendance is broadly in line with national averages, or improving towards them. That phrasing has two consequences. You need your figure next to the published national figure. Put your local authority's beside it too, for a fairer comparison. And you need direction over time, not a single snapshot. A school below national but improving is answering the question differently from a school below national and flat. Inspectors also ask what you do about persistent absence. Being able to name the pupils, and say what has been tried, is worth more than the percentage.
What attendance information do governors need?No names
Enough to hold the school to account, and no pupil named. Governors need four things. The whole-school figure and which way it is moving. The persistent and severe absence counts. How both compare with national and local authority figures. And any group sitting well behind the school's own average. They do not need a list of children, and should not be given one. Naming a child to a governing body shares something personal with people who cannot act on it. Governors decide on strategy and resources, not on individual children.
How do you tell a real attendance pattern from noise?Whole school
Check whether it holds across the whole school, not just one class. A single weekday standing clear of the others in every year group is almost never about families. It is usually timetable, transport, or something that happens on that day. Mornings against afternoons works the same way. A whole-school lean towards afternoon absence points at lunchtime, or at the last lesson, rather than at getting children out of the house. Check both before you start conversations with parents. The fix may not involve parents at all.
Can a multi-academy trust compare attendance across its schools?Yes
Yes, as long as you compare like with like. Persistent absence rates travel between schools better than whole-school percentages do. A primary and a secondary in the same trust are not really comparable on a raw figure. Compare each school against its own local authority average, not against its sibling schools. That separates the school that is genuinely behind from the one with a harder intake.
What data do you need to analyse attendance properly?3 exports
Less than people expect. Session-level marks with their dates and DfE codes. And enough pupil identity to group and name them: first name, last name, unique pupil number, year group and registration group. Every one of those is already a column in the attendance reports your MIS produces, the system your registers live in. You do not need dates of birth, addresses, contact details or any free text. A system that asks for them is collecting more than the job requires.
Where these definitions come from
Government sources, reviewed on 23 August 2026. Attendance policy moves, so the date is here for a reason. Use it to judge whether to check the live pages rather than take our word for it.
Our page, not the DfE's. The six stages the guidance sets out before a penalty notice, and the practices schools use to stay well clear of the threshold.
Doing all of this from a spreadsheet?
adsum works the answers above out of the exports your MIS already produces. That is the point: the data is already yours, and almost unreadable where it sits. Who is drifting below your target. Which families to reach before a fine is discussed, and in which ten weeks. Which patterns are real. And the reports for governors and inspectors, already written. Made by iCT4 Limited, with attendance leads rather than for them.