Unnecessary additional info:
It's simply an abbreviation for "mervärdesomsättningsskatt" which has kind of become its own word. The same abbreviation is used in Danish (meromsætningsafgift) and Norwegian (merverdiomsetningsavgift) so it's not a uniquely Swedish word.
Just registered to say thanks and express my gratitude, I love you for doing this! :D
I'll wait patiently for the (near) finished version before I try it out myself though.