The Goa Value Added Tax (VAT) Act, 2005 outlines definitions essential for understanding VAT, including concepts such as business, dealer, goods, and taxable turnover, along with regulations on dealer registration and tax liability. It details the circumstances under which a dealer must register for VAT and stipulates registration fees based on turnover limits, valid for three years, with penalties for late renewal. The document also elaborates on the calculation of input tax credit, output tax, and conditions for taxation on declared goods and works contracts.