The funding system
Schools receive funding from the Department for Education. This includes: baseline funding (per-pupil funding), deprivation funding, and a top-up from the local authority for pupils with high-need SEN. The baseline is meant to cover educating all pupils, including those with low-level SEND. High-need pupils with EHCPs get a top-up from the local authority. Schools also have their own SEND budget from which they provide SEN support (for pupils without EHCPs). Specialist schools receive much higher per-pupil funding. Early years provisions and colleges receive separate funding.
Notional SEND budgets
Schools have a "notional" SEND budget - money that's meant to support all children with SEND (those without EHCPs). The school is supposed to use this to provide SEN support and adaptations. However, schools often don't ring-fence this money - it gets spent on other things. This is why SEN support is often inadequate and why EHCPs (which guarantee specific funding) are so important. Your EHCP secures dedicated funding for your child in a way SEN support doesn't.
High-needs funding and "top-up"
When a child has an EHCP, the local authority provides a "top-up" to the school (or other provider) to fund the EHCP provision. The amount of top-up depends on the cost of provision and varies between LAs. Some pupils with the same needs might get different top-ups in different areas. This creates postcode lottery problems. Some LAs are generous and properly fund provision; others are stingy and under-fund EHCPs. This is a major issue in SEND.
Why funding is always inadequate
SEND funding has not kept pace with the increasing number of children with SEND. More and more children are identified as having SEND, but funding hasn't increased proportionally. Schools' overall budgets are squeezed. LAs' SEND budgets are often in deficit (spending more than they've been allocated). The result: SEND support is rationed. Schools avoid carrying out EHCP assessments because it commits them to funded provision. LAs try to refuse EHCPs or issue EHCPs with minimal provision. This is a systemic problem, not a local quirk.
How this affects you
Know that your LA may be reluctant to assess or issue an EHCP because of funding pressures - not because your child doesn't need one. This is not a legitimate reason to refuse. The law is clear: if the child needs an EHCP, they must have one, regardless of funding constraints. If your LA is refusing EHCPs due to cost, that's a grounds for complaint to the ombudsman and the DfE. Don't accept cost-cutting disguised as "eligibility" decisions.