A fixed charge is a type of charge. That is fixed. It doesn’t, so to say, float.
A fixed charge encumbers asset it secures from day one. To benefit from a fixed charge you need to have control over the assets - if the debtor can deal with the secured assets as it pleases without your knowledge and control, your fixed charge may fail - see Re Spectrum Plus. On a good day it might get recharacterised as a floating charge — but don't bank[1] on it and note that there are certain formal requirements to perfect a floating charge which you are likely not to have done, seeing as you were thinking what you had was a fixed charge which didn’ require them[2].
practically, because you do (right?) keep control over the asset and can prevent the debtor salting it away, and
legally, because it ranks ahead of a floating charge in the debtor’s insolvency (well - it would do: the first in time prevails, and by definition, a floating charge only fixes when it crystallises, meaning a floater is always last to the party). The converse is that the holder of a floating charge remains subject to the theoretical risk that another creditor will take a fixed charge over the same assets, and this will take priority over the floating charge when it subsequently crystallises.
Well, thereby hangs a tale. Recent case law — especially obiter dicta in the extended liens case, has thrown the area into confusion and now sainted legal counsel are scrambling to caveat views they might in gladder days have issued in bare-knuckle fashion. But even if you have delivered your collateral to a custodian and impressed with a fixed security interest in favour of a creditor, an generalised right to substitute that collateral might interfere with the control analysis.
Fixed charges are good for
Buildings
Plant
immovable forces
Custody assets (where the charge holder is the Custodian)
