Interim Headteacher or Supply Leadership: What Is the Difference?

A practical guide for proprietors, boards and trustees

Both put an experienced leader in your school when yours isn’t there. The cost is different, sometimes considerably, and boards understandably ask what they’re paying for.

Many proprietors tell us they commissioned supply leadership cover for a situation that needed an interim, discovered the difference in week three, and had to start again. It’s an easy mistake and it’s avoidable once you know what separates them.

What is the difference?

Supply leadership keeps the school running. Interim leadership changes something.

A supply leader covers the role. They keep the timetable working, the decisions flowing and the building open, and any inspection preparation already under way continues as planned. The brief is continuity, and success means the school is in the same condition when the substantive head returns.

An interim leader arrives with a brief. They’re expected to assess the school, name what’s wrong, address specific things and hand over a setting in better condition than they found it. Success means something is different.

Everything else follows from that distinction: the cost, the authority, the length and what you should expect.

How do they compare in practice?

Length. Supply cover is typically days to a few weeks. Interim placements run a term to a year.

Brief. Supply has none beyond keeping things running. An interim should have three or four written objectives.

Authority. A supply leader usually operates within existing arrangements and refers anything significant upward. An interim needs genuine delegated authority in figures, because they can’t deliver a brief without it.

Assessment. Supply leaders aren’t expected to evaluate the school. Interims are, and a board that doesn’t want an honest assessment has commissioned the wrong thing.

Cost. Supply is cheaper per day. The market prices assessment, accountability and risk, and supply carries less of all three.

Selection. Supply cover is matched on availability and general competence. Interim appointments should be matched on specific setting experience, because the brief depends on it.

When is supply leadership the right choice?

More often than boards think, and it’s frequently the sensible economy.

Where the absence is short and defined: a head off for three weeks after surgery, a two week gap before a permanent appointment starts, a period of compassionate leave.

Where the school is stable. No regulatory pressure, no live investigation, no significant improvement work in progress.

Where there’s a functioning senior team who need someone to sit above them briefly rather than someone to change anything.

Where the substantive head is returning. Nobody should be reshaping a school that its permanent leader is coming back to.

In those circumstances, commissioning an interim would be over-buying. Supply cover is the right answer and there’s no reason to feel it’s second best.

When do you need an interim?

Where the school needs something to change, or where the situation is genuinely uncertain.

A permanent vacancy with recruitment ongoing. A school with unmet standards or a poor inspection outcome. A suspension or investigation. A leadership departure that was difficult. Open ended absence with no known return date. Or a board that doesn’t actually know how the school is doing and needs an honest read.

That last one is worth naming, because boards rarely commission for it and it’s frequently the most valuable thing they get. An experienced leader who spends six weeks in a school and writes an honest account of it gives a proprietor something no amount of reporting from inside the school will.

The mistake in the middle

The costly version isn’t choosing one or the other. It’s commissioning supply and expecting interim outcomes.

A board covers a vacancy with supply leadership because it’s cheaper, then becomes frustrated in week four that the compliance actions haven’t moved, the improvement plan is untouched and nobody has told them anything they didn’t know.

The supply leader has done exactly what they were asked. Nobody set a brief, nobody gave them authority, and nobody said anything was expected beyond keeping the school running.

The reverse happens too, though less often: commissioning an interim at interim rates for a three week absence where nothing needs to change. That’s over-buying, and a good provider should tell you so.

What is the same regardless?

The safeguarding position, and it’s non-negotiable in both cases.

Full safer recruitment checks: enhanced DBS with barred list, prohibition checks, identity, right to work, references taken up directly. An entry on the single central record from day one. A recorded safeguarding induction before they meet pupils.

A short placement changes none of this. Neither does the person coming through a provider. We find gaps here more often with supply cover than with interim placements, precisely because it feels temporary and administrative.

Both also need clarity about who holds the designated safeguarding lead role during the cover, and that person needs current training for it.

From our experience

The most common error is boards buying on price without asking what they need to be different at the end.

The question that resolves it is simple: when this person leaves, what should have changed? If the answer is nothing, the school should just have kept running, that’s supply cover and you’d be over-buying anything more. If the answer names three things, that’s an interim placement and supply cover won’t deliver it at any price.

Many proprietors tell us they’d never articulated that question before someone asked it. Once they had, the decision took two minutes.

We also see supply cover extend informally into interim territory. A three week arrangement runs for two terms, the school starts expecting more, and nobody revisits the brief or the terms. Where that happens, convert it properly rather than letting it drift.

A common misconception

“Interim leadership is just expensive supply cover.”

It’s an understandable reading when you’re comparing two day rates on a page, and it misses what the difference is for.

You’re not paying more for a better person. You’re paying for a different job: an honest assessment of your school, accountability for delivering a brief, the willingness to tell a board uncomfortable things, and specific experience of settings like yours.

Where you need those, supply cover won’t provide them however good the individual is, because nobody asked them to. Where you don’t need them, supply cover is the right answer and spending more would be wasteful.

The children in the school need whichever genuinely fits their situation. A school that just needs to keep running for three weeks is well served by supply cover. A school that has stopped improving needs someone whose job is to change that.

Questions for proprietors and boards

• When this person leaves, what should have changed?
• Is the substantive head returning, and would reshaping the school help or hinder that?
• Have we written a brief, and does the arrangement give authority to deliver it?
• Are the full safer recruitment checks complete and on the record, whichever we’ve chosen?
• If supply cover has been running for months, should we convert it properly?

Our perspective

Both are legitimate and the choice should follow from what the school needs rather than from what the budget prefers.

Ask what needs to be different at the end. If the answer is nothing, buy supply cover and don’t apologise for it. If the answer names specific things, buy interim leadership, write a brief and give real authority.

What doesn’t work is buying one and hoping for the other, which costs a term and leaves everyone frustrated. Being clear about which you need takes two minutes, and it means the children in your school get leadership that actually fits the situation they’re in.