This is because the role of these two kinds of vouchers are not the same, donation vouchers is to prove that you donate, invoices are to prove that you donate things worth how much money.
In accordance with the provisions of Announcement No. 9, direct donations to the designated hospitals can also be deducted before tax, vouchers are hospitals issued by the donation of the letter of acceptance, from the current network on the letter of acceptance of the point of view, are only written varieties and quantities, such as masks a box, gloves, such as two boxes. The same is true for the letter of acceptance issued by the government. Therefore, the receiving letter can only prove that you did donate.
How much does what you donate cost, or how much can you deduct before tax, depends on the invoice, which is also based on the policy.28 Announcement IX states: "The expenditure items incurred by enterprises in the territory belong to the VAT taxable items, and the other party is a VAT taxpayer who has already applied for tax registration, and the expenditure is based on invoices (including invoices issued by the tax authorities in accordance with the regulations). The enterprise shall take the invoice (including the invoice issued by the tax authority on behalf of the taxpayer in accordance with the regulations) as the pre-tax deduction voucher;" the purchase of masks belongs to the VAT taxable items, and the enterprise shall take the invoice as the pre-tax deduction voucher.
As for individuals, Circular 99 says that "donations of non-monetary assets other than equity and real estate shall be determined in accordance with the market price of the non-monetary assets." The market price of the masks donated by individuals is the purchase price, so whether individuals need to purchase invoices for pre-tax deductions, Notice 99 does not say.
In summary, at least for enterprises, purchased materials for donation (whether through public welfare organizations or direct donations), both to obtain donation vouchers (you donate), and to obtain purchase invoices (how much money), one or the other is indispensable. Although the owner of this museum has never doubted the love of the donors, and do not believe that they will inflate the amount of expenditure, but the tax policy is so, try to comply.