增值发票是企业在销售商品或提供劳务过程中开具的一种税务凭证。根据增值税法规定，企业可以通过增值发票来抵扣应纳税额，从而达到减少税负的目的。然而，增值发票能够抵扣多少税款并不是固定的，而是根据不同的情况而有所变化。

首先，企业可以通过增值发票抵扣进项税额。所谓进项税额，指的是企业在购买商品和接受劳务过程中支付的增值税。企业在购买原材料、设备、劳务等方面产生的增值税可以通过增值发票进行抵扣，从而减少企业应缴纳的税款。具体来说，企业可以将购买商品或接受劳务的增值税额与销售商品或提供劳务的增值税额进行抵销，只需补交销售额超过进项税额的差额即可。这种方式被称为“按月抵扣”，企业可以在每个月的税款申报中进行相应的抵扣。

Firstly, enterprises can offset input tax through value-added invoices. The so-called input tax refers to the value-added tax paid by enterprises in the process of purchasing goods and receiving services. The value-added tax incurred by enterprises in the purchase of raw materials, equipment, and services can be offset through value-added invoices, thereby reducing the amount of tax payable by enterprises. Specifically, enterprises can offset the value-added tax incurred from purchases against the value-added tax generated from sales, only needing to pay the difference if the sales amount exceeds the input tax amount. This method is called "monthly offsetting," and enterprises can carry out corresponding deductions in their monthly tax declarations.

其次，企业可以通过增值发票抵扣留抵税额。所谓留抵税额，指的是企业无法当期抵扣的进项税额，可以延期抵扣到后续期间。企业在某些情况下，由于销售不同步或者没有销售，使得当期的进项税额无法完全抵扣，剩余部分即为留抵税额。这部分留抵税额可以通过增值发票进行抵扣，延期抵扣到后续期间。企业在以后的税款申报中可以使用留抵税额进行抵扣，减少应缴纳的税款。

Secondly, enterprises can offset the carryforward tax through value-added invoices. The so-called carryforward tax refers to the input tax that cannot be offset in the current period and can be carried forward to subsequent periods. In certain situations where the sales are not synchronized or there is no sale at all, the input tax for the current period cannot be fully offset, resulting in a remaining amount as carryforward tax. This carryforward tax can be offset through value-added invoices and carried forward to subsequent periods. Enterprises can use the carryforward tax to offset their tax payable in future tax declarations, reducing the amount of tax payable.

需要注意的是，增值发票只有在符合相关规定的情况下才能进行抵扣。企业需要确保所购买的商品和接受的劳务是用于应税销售或劳务提供的，并且符合国家税务部门的规定。同时，增值发票的开具和填写也需要符合相关的规定，包括发票的合法性和准确性。

It should be noted that value-added invoices can only be offset under certain conditions. Enterprises need to ensure that the purchased goods and received services are used for taxable sales or service provision and comply with the regulations of the national tax authorities. At the same time, the issuance and completion of value-added invoices also need to comply with relevant regulations, including the legitimacy and accuracy of the invoices.

总而言之，增值发票是一种重要的税务凭证，可以帮助企业减少税负。通过增值发票，企业可以抵扣进项税额和留抵税额，从而减少应缴纳的税款。然而，具体能够抵扣多少税款取决于企业的实际情况和遵守相关规定的程度。因此，企业需要充分了解相关政策和要求，确保合规操作，并提高税务筹划的效益。

In summary, value-added invoices are important tax documents that can help enterprises reduce their tax burden. Through value-added invoices, enterprises can offset input tax and carryforward tax, thereby reducing the amount of tax payable. However, the specific amount of tax that can be offset depends on the actual situation of the enterprise and the extent to which relevant regulations are followed. Therefore, enterprises need to fully understand the relevant policies and requirements, ensure compliance in operations, and enhance the effectiveness of tax planning.