(a) express acknowledgement of debt in writing
(b) acknowledgement of debt by payment of interest; and
(c) acknowledgement of debt by partial performance.
If the debtor acknowledges the debt, he creates a rebuttable legal presumption that the debt is still owed and the burden of proof is on him to rebut these facts, i.e. to argue, for example, that the debt was not incurred at all or no longer exists. At the same time, the acknowledgement of the debt has an effect on the running of the limitation period, whereby the creditor’s right is time-barred by the acknowledgement of the debt ten years after the date on which the debt was acknowledged.
An acknowledgement may also be made of a debt that is already time-barred, but in this case a written form is required. The written acknowledgement of the debt must indicate what debt is acknowledged and to what amount, ideally what the original debt was, what amount the debtor has already paid and by when the debt is or should be repaid. It must also contain a promise by the debtor to pay the debt. If it does not meet all the requirements, it may be considered by the court to be an alteration of the contract
In most cases, a written acknowledgement of debt will not cause major problems if it is properly drafted, but beware of acknowledging a debt by paying interest or partial performance. An implied (i.e. not in writing but based on the debtor’s conduct) acknowledgement of debt cannot be made where the creditor’s claim is already time-barred. The payment of interest or partial satisfaction of the debt, if any, will, even in this case, lead to the extinction of the relevant part of the debt, but it will not lead to recognition of the debt. Even the payment of interest does not in itself mean that the debtor acknowledges the debt. If the debtor indicates that he or she does not acknowledge the debt when paying interest, the payment of interest will not lead to recognition of the principal, but the debtor’s passivity is usually a sign that he or she does acknowledge the debt. In general, if the debtor pays part of the debt without disputing the rest of the debt and it does not appear from other circumstances that he does not accept the debt in the amount in question, he acknowledges the debt in its entirety.
Even a unilateral set-off which, because of its invalidity, does not lead to the extinction of the mutual claims is not in itself an acknowledgement of the debt within the meaning of Section 2053 or 2054 CC.