Offline showrooms develop rapidly to resolve consumers’ uncertainty about whether products fit their needs when they purchase online. This paper considers a supply chain where an offline showroom provides experience service for an existing online retailer and intends to introduce a new competing online retailer to satisfy consumers’ heterogeneous demand. The offline showroom has better knowledge of demand information due to closer to offline consumers. We examine the impact of competition and the offline showroom's optimal channel cooperation strategy under asymmetric information and analyse the equilibrium results under the optimal strategy to shed light on channel cooperation and information strategy for supply chain members. We find that under asymmetric information competition prompts the offline showroom to conceal information which generates signal cost (negative information effect) and to increase experience service level which creates value (positive service effect). The optimal channel cooperation strategy depends on the trade-off between these effects. We also find that competition increases the existing online retailer's profit in some conditions. Besides, in some conditions information asymmetry harms all supply chain members, which suggests the offline showroom to share information with the online retailers; in some conditions, information asymmetry harms the offline showroom but benefits the online retailers.

This study explores the optimal information-sharing strategy in a cross-border e-commerce supply chain with uncertain tax rates, in which an overseas manufacturer invests in product quality and a cross-border e-retailer holds private demand information. By establishing a game-theoretical model, we investigate the e-retailer’s motivation for sharing information with the overseas manufacturer and further explore the role of information sharing under tax uncertainty. Our results show that when quality elasticity is high, the e-retailer chooses to share its information voluntarily. However, under medium quality elasticity, the e-retailer shares information voluntarily only when the probability of the high tax rate is below a certain threshold. Moreover, the e-retailer could be more likely to share information under higher tax uncertainty. When quality elasticity is low, the e-retailer is unwilling to share information, but the overseas manufacturer can design a contract to incentivize the e-retailer to share information to realize a win–win outcome. Finally, we reveal that information sharing can mitigate the negative effect of tax fluctuation on the e-retailer’s profit. These findings provide useful implications for cross-border e-retailers on how to formulate information-sharing strategies under tax uncertainty arising from trade policy adjustment. Our study also supplements the information-sharing literature by discussing tax uncertainty, which is an important factor affecting the operation of cross-border e-commerce supply chain.