But it's not something that was written once and has been used as-is for 40 years – it has constantly changed to match the tax code. The IRS has claimed that i

But it's not something that was written once and has been used as-is for 40 years – it has constantly changed to match the tax code. The IRS has claimed that it is difficult for them to find engineers who can maintain it. After all, they didn't start a major project to port it to Java for no reason. I also disagree with Mayer's assertions about LOC. In my professional experience, the best ways to avoid bugs are optimizing for clarity as well as continuously grooming your codebase (including modernizing when possible). Obviously the latter is not an option for safety-critical software, and probably not suitable for the tax system either. But in general, those practices have worked better for me than have others.