Some of the reasons why you may be denied for payday loans include identity verification, past borrowing history, bank or address validation failure, credit check decline, employment type, existing loan agreements with other lenders. Make sure you have a good credit score before requesting a loan. Keep credit file up-to-date with correct information. If you have a low credit score, improve your credit rating over time by paying all your outstanding bills and debts on time. Close down the store cards and credit cards not in use. If you have a mortgage or joint account with a person having poor credit score, dissociate yourself. It’s best not to submit several credit applications in a short period of time but when it’s urgent. 

Source: How to Prevent Being Denied Online Payday Loans