中文：

计税依据偏低是指纳税人在计算应纳税额时所依据的计税依据明显低于正常水平。在税收征管中，如果纳税人采用不合理的手段来降低计税依据，以达到少缴税款的目的，这种行为通常会被认定为偷税行为。

计税依据偏低的表现形式有多种，比如虚构购销合同、伪造账簿和会计凭证、编造费用凭证等。这些手段都是为了虚增成本或者隐瞒收入，从而达到降低计税依据的目的。

对于计税依据偏低的问题，税务部门通常会采取一系列措施进行治理。首先，加强对纳税人的监管力度，严格审核其财务报表和相关凭证。其次，开展专项检查，对存在疑点的纳税人进行深入调查。最后，加强处罚力度，对查实的偷税行为进行严厉惩处，以维护税收征管的严肃性和公正性。

英文：

The low basis for taxation refers to the situation where the basis for taxation used by taxpayers in calculating tax liabilities is significantly lower than normal. In tax administration, if taxpayers use unreasonable means to reduce the basis for taxation in order to reduce tax payments, this behavior is usually considered tax evasion.

There are various forms of low basis for taxation, such as虚构购销合同、伪造账簿 and accounting vouchers, and falsification of expense vouchers. These measures are taken to inflate costs or隐瞒income, thereby reducing the basis for taxation.

For the problem of low basis for taxation, the tax department usually takes a series of measures to address it. First, strengthen supervision of taxpayers and strictly review their financial statements and relevant vouchers. Second, carry out special inspections and conduct in-depth investigations on taxpayers with suspicious points. Finally, strengthen punishment and severely punish identified tax evasion to maintain the seriousness and fairness of tax administration.