It was nothing to finalize open years 10 years after the fact. For example, in the year 2019, you may have “open audits” on indirect rates (Overhead, G&A, etc.) that have not been finalized from 2009 onward. Therefore, we could bill the government only with “provisional rates”. If the actual rates finally audited and agreed to by the company is less, the government was owed money. If the rates turned out to be more, we could bill for the difference.
Trump ran a multi billion dollar industry —it's not like he's using Turbo tax to do his taxes. He employs legions of tax accountants and tax lawyers, lawyers that specialize in real estate, labor law, etc. This is complicated business and if any of the tax laws are retroactive, then tax filings have to be updated and re-filed.
Nothing is easy peasy here. I fully understand that it's taking lots of time. And someone like the NYT trying to make this a simple, direct issue are ignoramuses.
Loss years that are being carried over are still subject to scrutiny. Carryover can be 20 years.