No — and it's not just a guideline. Here's exactly where the line is and what happens if you cross it.
A skip is legally full when waste sits level with the top edge of its sides — not mounded above it. This is the line the driver has to check before it can be transported on a public road.
An overfilled skip is a genuine road safety issue — loose material can fall from a moving lorry. Because of this, licensed carriers are legally required to refuse transport of a skip loaded above its rim.
The driver will usually ask you to remove the excess before collection, or do it themselves for an extra charge. In some cases they'll refuse to collect at all until it's within the limit, which can mean the skip sits on site longer than planned.
Break down bulky items (flatten boxes, dismantle furniture) so waste settles rather than stacking upward. If you're consistently close to the line, it's a sign you should have ordered one size up — sizing up is almost always cheaper than the hassle of an overfilled skip.
Dense material like soil, rubble and tiles can max out a skip's legal weight limit long before it looks visually full. If that's most of what you're disposing of, ask your supplier about a dedicated heavy-waste skip rather than judging by how full it looks.