We analyze theConcordatoPreventivoBiennale(CPB), a two-year advance tax agreement between the taxpayer and the tax agency on fixed income tax liabilities, introduced in Italy in 2024 with the aim of promoting collaborative tax compliance among small businesses and self-employed workers. Within a tax evasion model, we first characterize which types of taxpayers are more likely to take up the CPB on the basis of their risk attitudes and exposure to income uncertainty. We then show how the CPB can be designed -- using observed past income declarations as well as other signals of taxable income -- to increase both tax collection and taxpayer welfare.