how to categorize income

It depends on exactly what that refund was for; and the type of entity your company is.       For example: If you are are an S-Corp and have employees then you are paying payroll taxes to the IRS.   So if you overpaid them (941 taxes)  the refund should go back to the same Payroll Tax expense account.     Unless - you were expecting a refund because you knew you overpaid  - you may have set up an account on the Balance Sheet with a name something like "Due from IRS".

If you are a sole proprietor and have no employees; your business doesnt owe any tax.   You owe tax personally.  So if you received a refund it should be deposited in your personal account, not a business account.   But if the check has the business name on it ; then categorize it back to Owner Draws.