Tuffi (Pte.) Ltd. v Techkon Pte Ltd and another

Tuffi (Pte) Ltd and Techkon Pte Ltd were partners in a joint venture company, Techkon Development (Sembawang) Pte Ltd (TDSPL), originally held 49% by Tuffi and 51% by Techkon. TDSPL's earlier projects were profitable, but its stake in a residential development at 520 Balestier Road, the Viio Project, made losses. Tuffi could commit only a smaller share of the Viio funding, and the gap was filled by preference shares issued to outside investors, so that the two partners' effective contributions stood in the proportion of 15 to 36.

In February 2019 the parties signed a one-page set of calculations prepared on Tuffi's side to rebalance their positions. Through a series of items it arrived at $722,429.73 due from Techkon to Tuffi, plus $196,000 for Techkon buying shares that took the holdings to 29.4% and 70.6%, giving a final sum of $918,429.73, which Techkon paid. In January 2021, at Techkon's initiative, the parties discussed recalculating the figures, and Techkon proposed reducing the sum. In that process Tuffi found that the preference share expenses had been deducted twice. Corrected, the Tuffi balance would have been $1,256,962.89, and Tuffi sued for the difference of $534,533.16.

The High Court Judge dismissed the claim, holding that the agreement was to pay a fixed sum, that no term allowed adjustment, and that Tuffi was at fault for the error. Tuffi appealed in Civil Appeal No 108 of 2025. Before the Appellate Division, Techkon accepted that the double counting had occurred.

1. Whether the 2019 agreement was only to pay a fixed final sum, or also covered the calculations leading to it.
2. Whether the agreement should be rectified to correct the double counting of the preference share expenses.
3. Whether, alternatively, a term should be implied allowing the final sum to be adjusted for calculation errors.
4. Whether TDSPL was a party to the 2019 agreement and liable under it.

On interpretation, the court held that the agreement covered both the calculations and the final sum. The absence of a ruled line above the signatures meant nothing, Techkon conceded that obvious arithmetic slips could not bind it, and the sum was plainly derived from the items above it in a document all four men signed. This was not a bad bargain struck through negotiation but a shared calculation error. Techkon's own 2021 attempt to recompute the sum using the same formula confirmed it was not treated as fixed. However, reading the figure as a different number would cross from interpretation into variation.

On rectification, the court distinguished the defence of common mistake, which avoids a contract, from rectification, which corrects how an agreement was recorded. Applying Yap Son On v Ding Pei Zhen [2017] 1 SLR 219, the parties had a common continuing intention, outwardly expressed, to rebalance according to their Viio shares, and by mistake the final figure did not reflect it. Tuffi was not solely at fault: Techkon was asked to check the figures and held the accounts; it was an honest mistake neither side caught.

On the implied term, the court would in any event have implied a term allowing adjustment for calculation errors, since the parties had not contemplated the gap and would have answered "Oh, of course!".

On TDSPL, it was not shown to have signed in its own right, and the agreement in any case required Techkon alone to pay.

The Appellate Division allowed the appeal in part: it allowed Tuffi's claim against Techkon, rectifying the 2019 agreement so that the adjusted final sum was $1,452,962.89 and ordering Techkon to pay Tuffi $534,533.16 with interest as claimed, and dismissed the appeal against TDSPL. Costs were to be agreed or decided after written submissions.