Tacking (an old form of “attaching”) is a legal right most usually relevant when the common law resolves competing priorities between two or more security interests arising over the same asset.
The effect of the tacking is to postpone (i.e., demote) the rights of the first creditor to those of the second: this follows the general principle that a legal interest takes priority over an equitable one.
The wider applications of tacking, which concern equitable claims to property more generally, are clear in the definition given by Black's Law Dictionary: 1.
The joining of a junior lien with the first lien in order to acquire priority over an intermediate lien.Separately, in the definition of tabula in naufragio, Black's comments: It may be fairly said that the doctrine survives only in the unjust and much criticised English rule of tacking.The right to tack was established by Sir Matthew Hale in Marsh v Lee in 1670, apparently as “tacking tabula in naufragio”[2].
Mortgages are but contracts; and when once the rights of parties under them are defined and understood, it is impossible to say that any rule regulating their priority is unjust.
In 2014, the Court of Appeal of Newfoundland and Labrador held in Medoc Properties Limited v. Standard Trust Company[5] that the failure by an assignee to release one of two assigned mortgages with respect to such an agreement resulted in differing priorities given to them.
Then at a time when the overdraft stands at £100,000, the customer grants a second mortgage over their house as security for a term loan to another bank.
Accordingly, in practice a bank will normally "break" an account when they receive notice of a subsequent charge over property which stands as security for an overdraft.
[10] Ultimately, Hopkinson was thought to cause more inconvenience than it solved, and a number of common law jurisdictions have sought to modify the position by statute.