In the U.S., individuals are expected to file federal and state tax returns once a year by April 15. The tax forms are quite complicated, and have all sorts of sub-forms and schedules to support and detail the numbers on the main form. The tax code of the U.S. is approximately 74,000 pages of special cases.
For many items, the same data needs to be entered on multiple forms, usually as the starting point for different calculations that depend upon the same information; these are duplicated again on both federal and state returns. It follows that tax preparation software needs to put the relevant numbers in all the places that they are needed.
Why? Because if it doesn't, the preparer needs to manually copy numbers to each of several places, leading to all sorts of omission/accidental editing issues. Just to make it needlessly complicated interesting, in many cases, the numbers need to be transformed via some formula before copying, and the formulas vary from form to form, and from state to state. Complicating this process is the fact that tax forms stating your earnings from employers and financial institutions can be re-issued with new values if tax laws are changed too close to the end of the year. This means that new numbers need to be entered, propagated, calculated and checked on your tax forms, usually after they were initially prepared.
If you're preparing your own tax returns, then they probably aren't all that complicated, and there isn't too much copy/pasting to be done. If you have multiple businesses in different states/countries, multiple properties, use multiple banks/brokerages, etc., then there are many, many forms and worksheets detailing the same information, leading to a whole lot of copy/pasting of data. When the complexity of what must be prepared gets beyond a certain point, you go to a professional preparer who will just enter your information once, and the very expensive professional tax software will put the numbers on all the relevant forms automatically. This way, it only takes a few minutes to enter the data, hit calc and a mountain of completed tax forms spews forth from the printer.
Julie is a highly experienced accountant, and was partnering with a large, national chain of tax preparers that used their own in-house tax preparation software. They had a large IT team of several hundred assorted developers and support staff. Each year, they'd wait for Congress to decide on changes to the tax laws, and then begin the process of implementing those changes in their software so that they could get it to the accountants in time for tax season.
Unfortunately, Congress doesn't take programming time into account when they bicker back and forth over changes to the tax law. Last year, Congress passed a whole slew of changes at the very last minute, leaving insufficient time to implement all the changes in the software (at least not without the usual magic happens here programming of experienced developers). The solution that the blockhead managers came up with was to only implement part of each change prior to distributing the software. They called this "being agile".
When Julie started to prepare tax returns, she realized that the inputs to the same calculation were different on different forms. The numbers were not being propagated to the places that needed them, or worse, were being propagated incorrectly. Additionally, some calculations only performed the first 10 steps of a 12 step form. Upon raising bugs, she was told We know about these issues and have no plans to fix them!
Wait, manually propagating numbers and checking every calculation defeats the purpose of using the software in the first place; the numbers can't be close, they have to be exact and consistent across forms!
The debate about the importance of exact and correct calculations went back a forth and while until it was escalated sufficiently high to warrant an official response:
Our software is only intended to guide you in the general direction of preparing tax returns. It only needs to be reasonably functional, not "useful".
Julie, at this point, was desperate, so she contacted an insider at the company. "Is there *any* chance this is going to be working in time for tax season?"
"Oh, man… noooooo," her contact said. "A lot of the developers are on contract, so somebody ran the numbers comparing the hours of development time against paying penalties from audits. They figured out that they could do about… 90% of the changes. It's cheaper to just pay the penalties later."
Julie is no longer partnering with this conglomerate.