You can still get a Form 11 through your ROS inbox which is a copy of what is submitted to Revenue and this is usually part of what the bank requires
Within a day or two an Income Tax Self Assessment (ITSA) form will issue, which is essentially the P21 balancing statement or statement of liability for a non Income Tax registered individual
The Form 11 should match to what is on the ITSA, albeit more detail (Form 11 will have income and expenses, ITSA will just have taxable profits)
If your tax credits have been reduced then I believe you submitted what is known as a Form 12 as a non Income Tax registered person. An Income Tax registered person would typically have to pay the liability rather than have it offset by future tax credits. You may want to update the bank and they will then let you know what require for a non Income Tax registered person
Form 11 (Income Tax registered) - returns a Income Tax Self Assessment
Form 12 (non Income Tax registered) - returns a P21 balancing statement (also called statement of liability)