Your bookkeeping file (SIE format) is the basis for both the annual report and the tax return.
From bookkeeping file to submitted return.
You upload the SIE file from your bookkeeping once. The figures that both submissions need are read from it rather than typed in twice.
The result in the books is not the result that is taxed. The adjustments between the two are the part that takes the time, and the part the software is for.
Filed digitally to Skatteverket in the format they expect, rather than transcribed into a form by hand at the end of an already long evening.
The tax return is tightly coupled to the annual report — it is part two of the same job, and launches together with the annual report service.