If I recall correctly, there was a problem with one year not honouring the actual version. I usually use 9001 or 12001 but I haven't imported budgets in a few years. What version is in the file when you export the budgets? If it is what you are using, then try importing it back in again and see if it causes an error. I would do this on a copy of your file for testing.

Thanks for the good suggestion Richard. When I exported the budget file the version code was 22301. I was able to import it back into Sage. Unfortunately I then changed my version code in my .csv file to 22301, tried to import but got the same error code again. I could have probably inputted the budget manually by now after all the time I have spent on this ;)

Then my guess is the code itself is not the problem, but the syntax of the whole first line. Compare your's to the one you exported.