Article Processing Charges FAQ

1. What do I do if I get an error message when trying to pay by credit card?

Please contact your credit card provider if you receive an error message after attempting to pay by credit card, as this may be due to your card being blocked for international transactions.

2. What if I accidentally pay more or less than the invoiced amount?

In case you accidentally pay more than invoiced by MDPI, please contact us at and we will refund the overpaid amount, minus any bank or transaction charges. In case you accidentally pay less than the invoiced amount, another invoice will be issued to you for the remaining amount.

3. Does MDPI offer any discounts or waivers on the APC?

MDPI has an Institutional Open Access Program (IOAP) which grants authors affiliated with participating Institutions discounts on our APC.

Reviewers who provide timely and substantial comments will receive a discount voucher code entitling them to an APC reduction. Vouchers will be sent to reviewers only after the final decision of the reviewed paper is given. All valid and associated vouchers can be applied to one invoice.

Note that vouchers issued to specific individuals are not transferable. Only vouchers that were issued to one of the authors of the current paper are valid and must be mentioned during the submission process.

Please note that reviewer vouchers must be applied before acceptance for publication. Vouchers can no longer be applied once an APC invoice has been issued.

4. Where can I find and how can I apply the vouchers to a specific publication?

Discount vouchers will be shown under the Submissions Menu in the Discount Vouchers list. In order to be able to use all vouchers sent from MDPI, authors are allowed to link multiple emails to the current profile being used.

Please add your voucher code in the MDPI system when you submit your paper, then, you will automatically receive a reduction on the APC.

Furthermore, MDPI publishes selected articles invited by the Editorial Office for free. Waivers may be granted at the Publisher's discretion. The editorial decision making is decoupled from the authors' ability to pay the Article Processing Charges in case their paper is accepted for publication.

5. How can I revise my invoice?

MDPI allows the corresponding and submitting author to update the invoice information by following the link provided in the invoice email or in the Submissions Menu under Invoices.

6. Do I Have to Pay if My Manuscript is Rejected?

No. MDPI only sends the invoice for article processing charges (APCs) if a manuscript has been accepted for publication. The acceptance of a manuscript is based on the outcome of the peer-review procedure. The final decision as to whether a manuscript will be accepted for publication or rejected is made by an external editor (usually the Editor-in-Chief of a journal or the Guest Editor of a special issue) based on scientific merit.

7. Can I be refunded if my paper is rejected?

Any service prices paid before the final decision will be refunded to the customer minus the payment transfer charges with the exception of English editing charges. Customers are also allowed to transfer the paid services to another article in case of rejection.

8. Can I pay in advance (before acceptance)?

MDPI provides an option for payment in advance if the customer’s budget funds may expire before the final decision of the paper is provided. Such agreements should be organized with Editorial Office of the relevant Journal. The MDPI Accounts Department will send an invoice (Proforma) in advance if requested. Please note that any advance payment will not affect the final decision of whether an article is accepted for publication.

If the paper is then rejected, MDPI will issue a refund upon request deducting the bank fees or the customer could choose to keep the amount as pre-payment for another publication.

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