Article 159 bis 18 sets a tighter filing deadline for small businesses compared to standard corporate taxpayers. Enterprises must submit their annual income return within three months of the end of the tax year (standard taxpayers have four months). The return must be officially signed according to the procedures mentioned in Article 134. This three-month deadline ensures that the Tax Authority can process the high volume of small business filings earlier in the year, facilitating prompt revenue collection and status verification for the SME sector in Oman.