Tacking is a technical legal concept arising under the common law relating to competing priorities between two or more security interests arising over the same asset. The concept is best illustrated by way of example.

1. Bank A lends a first advance to the borrower, which is secured by a mortgage over the borrower's property. The mortgage is expressed to secure this advance and any future advances.
2. Bank B subsequently lends more money to the borrower, and takes a second ranking mortgage over the same property.
3. Bank A then subsequently lends a second advance to the borrower, relying upon its original mortgage.

Bank A will always have a first priority claim against the property for the full amount of its first advance. However, it will only be able to claim against the property in priority to Bank B with respect to its second advance if it is permitted to tack the second advance to the mortgage which was taken at the time the first advance was made. If Bank A is not permitted to tack the second advance, then Bank B's claim in respect of the sums which it lent will have priority over Bank A's claims with respect to the second advance.

In American jurisprudence Black's Law Dictionary defines tacking in slightly narrower terms:

"The uniting of securities given at different times, so as to prevent any intermediate purchaser from claiming a title to redeem or otherwise discharging one lien, which is prior, without redeeming or discharging the other liens also, which are subsequent to his own title. The terms is particularly applied to the action of a third mortgagee who, by buying the first lien and uniting it to his own, gets priority over the second mortgagee."

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 common law rules

The first case which approached the position in relation to competing mortgagees was Gordon v Graham (1716) 2 Eq Cas Abr 598. Surviving reports of that case are extremely short, and during the nineteenth century, the authority of the decision came to be doubted. It was questioned whether it had been correctly reported and, even if correctly reported, whether it correctly stated the law.

The matter subsequently came before the House of Lords in Hopkinson v Rolt (1861) 9 HL Cas 514, 11 ER 829. In the case the borrower entered into a mortgage over his land which was expressed to "secure the sums due and which shall from time to time become due" to the bank. Later, the borrower granted a second mortgage in favour of another creditor. Notice of the second mortgage was given to the bank. The borrower was later declared bankrupt, and a dispute arose as to the priority of the bank with respect to advances which were made under the first mortgage after it had received notice of the second mortgage.

The three law lords who heard the case were divided, with a majority favouring priority for the second mortgagee. Lord Campbell, the Lord Chancellor, opined:

"I must say that the doctrine [in Gordon v Graham] seems to me to be contrary to principle. Although the mortgagor has parted with the legal interest in the hereditaments mortgaged, he remains the equitable owner of all his interest not transferred beneficially to the mortgagee, and he may still deal with his property in any way consistent with the rights of the mortgagee. How is the first mortgagee injured by the second mortgage being executed. . . ? The first mortgagee is secure as to past advances, and he is not under any obligation to make any farther advances (emphasis added). He has only to hold his hand when asked for a farther loan. Knowing the extent of the second mortgage, he may calculate that the hereditaments mortgaged are an ample security to the mortgagees; and if he doubts this, he closes his account with the mortgagor, and looks out for a better security.

Lord Chelmsford agreed with Lord Campbell.

The dissenting judge, Lord Cranworth, was in favour of upholding the rule in Gordon v Graham as it was reported. He expressed his view in a dissenting opinion:

"I certainly had understood that in such a case, excluding all special circumstances, the first mortgagee would be secure for any subsequent advances covered by his security, even though he had notice of the second mortgage. This is so laid down on authority, has, I believe, been often acted on, and seems to me perfectly just and reasonable.

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. If the law is once laid down and understood, that a person advancing money on a second mortgage, with notice of a prior mortgage covering future as well as present debts, will be postponed to the first mortgagee, to the whole extent covered or capable of being covered by the prior security, he has nothing to complain of. He is aware when he advances his money, of the imperfect nature of his security, and acts at his peril.

...

The rule ... is a convenient rule, causing injustice to no one. It has, probably, been often acted on, and to depart from it may, I think, retrospectively cause great injustice, and prospectively prevent advances of money by bankers or others, where such advances might be safely and usefully made"

Actual notice

Although for years it had been supposed that it was sufficient for the first mortgagee to have either actual or constructive notice of the second mortgage, in Westpac Banking Corporation v Adelaide Bank Limited [2005] NSWSC 517 it was held that constructive notice was not sufficient, and that a first mortgagee could tack future advances unless it had actual notice of the second ranking security.

Term loans and overdrafts

The common law rules relating to tacking caused most difficulty in relation to overdrafts and revolving loan facilities. This was because of another common law rule: the rule in Clayton's Case. That rule provided that in relation to any account, payments into the account are presumed to discharge the earliest debts first. The rule is only a presumption of convenience, but in practice it is difficult to displace, and can have a devastating effect on the security rights of first mortgagees.

For example, suppose a customer secures an overdraft with a mortgage against their house. 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. If over the following nine months, the customer was to pay £90,000 into the account and draw a further £70,000 out of the account, the amount owed to the first bank would be reduced to only £80,000, but they would only have first ranking security for a mere £10,000. For the remaining £70,000 they would rank behind the second mortgagee.

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.

Statutory modification

Ultimately, the decision was thought to cause more inconvenience than it solved, and a number of common law jurisdictions have sought to modify the position by statute (see for example, section 94 of The Law of Property Act 1925 in the United Kingdom, section 28 of the Law of Property Act 1929 of British Columbia and section 82 of the Property Law Act in Queensland).

Section 94(1) of the Law of Property Act 1925 of the United Kingdom provides:

After the commencement of this Act, a prior mortgagee shall have a right to make further advances to rank in priority to subsequent mortgages (whether legal or equitable):

(a) if any arrangement has been made to that effect with the subsequent mortgagee;

(b) if he had no notice of such subsequent mortgages at the time when the further advance was made by him; or

(c) whether or not he had such notice as aforesaid, where the mortgage imposes an obligation on him to make such further advances.

This subsection applies whether or not the prior mortgage was made expressly for securing further advances.

Footnotes

External links

• Report of the Law Commission of Alberta on the law of priorities, which contains an excellent discussion on the law of tacking
• Sibbles v. Highfern Pty Ltd (1987) 164 CLR 214, 76 ALR 13, the Australian High Court considering common law tacking rules