Advertising and promotional expenses incurred to market your online business are generally deductible as ordinary and necessary business expenses. This includes costs for digital marketing, website hosting, social media promotion, and other related advertising fees. The expenses must be directly connected to generating business income and supported by proper documentation. It is advisable to maintain detailed records and receipts. As tax law can evolve, consulting with a professional advisor to confirm the current deductibility criteria and any applicable limitations is recommended.