In accounting, the taxpayer is the one who must face a tax obligation, be it a natural person or a legal person. That is, he is the one who generates the fact or action for which he will later be forced to pay taxes.
In the case of a business for example and the Value Added Tax or VAT, who is the taxable person: the company or who makes the acquisition? In this specific case, the taxable person is the company, however, it is the customer who pays the tax. That is to say, the tax obligation is the company that sells the product (by law it must apply the corresponding% VAT) for this reason it is a taxable person, although later indirectly the one who pays the tax is the customer.
But this is not the case in all cases, for example, when a house is bought, the taxpayer is equivalent to the buyer, who voluntarily acquires the obligation to pay a tax in exchange for acquiring an asset, in this case, a home owned.