No, without his permission, this is not legal and can subject you to serious civil and criminal penalties. If somebody owes you money, you need to pursue judgement in court (small claims if the amount is small enough) or pursue other legal collection methods. You may want to speak with a debt collection attorney to assist you in this endeavor.
Disclaimer Information on this site is provided by Brian Scott Wayson as general information, not legal advice, and use of this information does not establish an attorney-client relationship. If you have questions about your specific situation, please call an attorney.
Are you a merchant? If so, merchant services at your bank may be able to tell you if a check in your possession would clear processing. You can't get bank account activity info using someone's account number and social security number unless you have written signed permission to do so and then you are only able to acquire credit report info, not bank account info. Using a phone line to access account information at a bank across state lines is not a game you want to play. Confronting someone to pay you money is difficult. I recommend that you contact your debtor and let him/her know you expect to get paid and that you will work out a payment plan with interest. Draw up a payment agreement, like a formal loan/promissory note. If a payment is missed proceed directly to court for enforcement and a judgment. Then you may purse other collections remedies like wage garnishment. Good luck.
This information is general and will change according to your facts. While this information may apply to your situation, without more facts I can not encourage you to rely on this information. I am not your attorney. No attorney client relationship exists. You should hire an attorney for your specific business matters.