First level of Verification is a Personal ID and a Bank Account Statement.
Second level of Verification is a piped utility bill or a business license and making sure your card is entered into Seller Central.
Third level of Verification is a video interview, where you get to show off your paperwork. Sometimes they send out a postcard with a verification number on it as well.

It seems like one of the more common issues with verification is that our new sellers have not entered a credit card in seller central. Rather they have put a debit or prepaid card in. I would check that first.

Below is a generic reply that covers most of the issues that I have seen our new sellers having with verification. A lack of response likely means that you are in a really long queue and they have not reached your submission yet. Amazon can take as long as 45 days to respond to your second or later submission.

1. You did not send the documents that they actually asked for. Many people send bank account information, landlord contracts, etc, instead of the utility bill that Amazon is asking for. Billing addresses on the utility bills and the Card need to match the address you opened the account with.
2. Your Name does not match exactly across all the documents. If one includes your middle name then they all need to. If you married and your last name changed and your documents do not match because of this, then you need to fix that then resubmit the documents.
3. Your Address does not match across all documents. For instance, North may be spelled out in one and another may simply use N instead. We have also found issues with documents having the 9 digit zipcode and the seller having entered only the first five on the account. This does not match for Amazon. The Name and Address must match your Legal Entity and Business Address entries in Seller Central.
4. You did not send all pages of the document. Make sure you also include front and backs of the pages.
5. Utilities are in someone else’s name.
6. You have not sent one of the utility bills or the business license that they specifically asked for. This bears repeating as I see it so often on the forums. Often people send multiple bills instead of one of the bills being asked for. If you can not follow their instructions for what they are asking for they will not even open the documents that you sent.
7. They do not accept screenshots. They do accept pics off of a camera on a phone.
8. Make sure the files are in .PNG, .JPG, .PDF, .DOCX, or .GIF format. Do not include non-standard characters in the file name such as *^$&+@. These documents must be authentic and unaltered, and the name and address on the document must match the name and address you provided during registration. If you are receiving electronic copies it is recommended to print them and then rescan them. Send the newly scanned copy. Make sure the PDF or pic is crisp looking, not blurry or smeared. All the pages of the bill should be in One file.
9. If Amazon had concerns regarding any authenticity from a utility bill, re-submitting the same one will likely get no response or the same rejection performance notification. Whether you take a high definition jpeg photo of your bill or you submit the utility bill direction downloaded in pdf format, always check for accuracy. Is all the information on the bill correct? Can you look up all the information to verify the authenticity the same way Amazon would? Is the complete bill provided and clear? Is it completely unaltered? If you cannot say an absolute yes on these questions, then you need to re-evaluate the utility bill you are sending. Graciously provided by @Darby_Amazon.
10. Documents submitted must be in one of these supported languages: Arabic, simplified Chinese, Dutch, English, French, German, Hindi, Italian, Japanese, Korean, Polish, Portuguese, Spanish, Tamil, Thai, Turkish, and Vietnamese. Any other language will need a notarized translation.
11. You are using a prepaid or debit card that is not acceptable when Amazon places its charge on it to confirm it is valid. Amazon accepts all debit and prepaid on the buyer side, but not necessarily on the seller side. They will bill the bad debit and prepaid cards, but the account will not become active until a proper credit card or acceptable debit card is entered. Debit cards have a range of permissions/functions depending on the bank, cardholder, etc. A debit card may or may not be accepted. Most debit cards from major US banks will likely be accepted. Apple Virtual Credit Cards are not accepted. Amazon is looking for the billing address on the card account.
12. No valid credit card on the account. This bears repeating as I see it so often on the forums.
    https://sellercentral.amazon.com/gp/help/help.html/?itemID=G861&ref_=ref_macs_cc_faq
13. To quote the request from Amazon for the second stage verification, _To reactivate your account, please confirm that there is a valid credit card on file and provide one of the following documents in PDF, PNG, JPEG, or GIF format. The documents must be legible, authentic, and unaltered and contain the required information.We do not accept screenshots. The name and address on the document must match the information entered in Seller Central.

–---- A business license if applicable

–---- A utility bill dated within the last 90 days for piped gas, natural gas, electricity, piped water, mobile phone, fixed-line phone, or internet service with name and address visible_

When Amazon says…
A. Please confirm that there is a valid credit card on file, and
B. provide the requested document(s) in .PDF, .PNG, .JPEG, or .GIF format. These documents must be authentic and unaltered.
…these are two separate requests.
When Amazon says ‘Valid credit card on file’ they mean to make sure it has been entered into Seller Central under ‘Account Info’ under ‘Charge Methods’. They are not asking for a credit card statement.
The document request is always a utility bill to be uploaded to Amazon. The document will vary from country to country.
Copied from a post by @papyrophilia
14. Amazon is now performing address validation on Cards. The address on the card now must match the billing entity address in Seller Central exactly.
15. If you are an international seller from outside the US, is your credit card open to international charges?
16. You can submit through the following page. sellercentral.amazon.com/performance/dashboard?ref=ah_em_comp

Amazon Seller Identity Verification Help Page
https://sellercentral.amazon.com/gp/help/help.html?itemID=QRP483PDN88Q3M9&ref=efph_QRP483PDN88Q3M9_cont_G2

Account Verification Utility Bill & Credit Card Questions
https://sellercentral.amazon.com/forums/t/account-verification-utility-bill-credit-card-questions/823501

Acceptable Credit Cards and Banking Information
https://sellercentral.amazon.com/help/hub/reference/19791

Oneida’s Assistance with Credit Card Issues
https://sellercentral.amazon.com/forums/t/i-need-your-help-account-got-deactivated/959738/5