Paying people to understand exactly what form that regulatory capital should take. Determining where it should be held. Proving to your regulators that you or someone you retain followed the proper procedure in determining how much and what kind of capital should be held. Demonstrating that the proper changes to those balances were made at the proper times and that an internal framework exists for making modifications as risk exposures shift. (And more and more and more.) Here's the simplest summary I could find of one of the many required compliance frameworks: https://www.bis.org/bcbs/basel3/b3_bank_sup_reforms.pdf