Is my spouse entitled to half a business I built on my own?

Under the default community of acquests regime that applies unless you specifically excluded it through a marriage contract, the Civil Code, Chapter 16 of the Laws of Malta, generally treats wealth and property acquired through either spouse's work or industry during the marriage as falling within the shared community, which can include a business built during the marriage, regardless of whether the other spouse was personally involved in running it, since the community of acquests principle is based on the marriage as an economic partnership rather than requiring both spouses to have directly contributed labour to a specific asset. However, the practical treatment of a business specifically can involve more nuanced considerations than simpler assets, since courts may need to distinguish between the value of the business itself as a community asset versus, in some cases, elements that might be considered more personal to your specific skills or professional standing, and the actual mechanics of how a business gets valued and divided, or whether one spouse buys out the other's interest, can be genuinely complex. Given the significant value and complexity likely involved in a business asset, it is important to engage a family lawyer, and potentially a business valuation expert, early on to properly understand how the community of acquests principle would realistically apply to your specific business in the context of your separation.