从１９９４年实行税制改革以来，增值税专用发票得到了广泛的应用。同时，也带来了一些问题，有些不法分子利用增值税专用发票进行偷税、逃税，给国家造成了巨大的损失，为了减少损失，打击犯罪，国家加强了对增值税专用发票的管理。在目前，利用协查函进行协查是一种行之有效 Since the introduction of the tax reform in 1994, special VAT invoices have been widely used. At the same time, it also brought some problems. Some criminals use tax-specific VAT invoices for tax evasion and tax evasion, which caused huge losses to the country. In order to reduce losses and crack down on crimes, the state stepped up the management of VAT invoices. At present, the use of investigation letters to conduct an investigation is an effective method