I do not have much of regular employment, I work shifts for various employers, so it is up to me how much I earn. However, typically the amount of work I do results in me earning about 550k NOK per year.
Last year, my tax card came in a way that made me pay way too little tax throughout the year. Realising this, I had to manually make my employers send more of my salary to the Tax Administration so that I would not fall behind and get a big bill from the Tax Administration due on May 15th this year.
I was thinking, though: Why should I do that? Maybe it is even better to take the opposite approach. Try to pay as little tax as possible throughout the year. This can be done by declaring that you estimate you will earn very little, and thus getting a very low tax rate.
I know that my real tax rate should be somewhere between 30% and 35%, so whatever I do not pay (but know I should really pay) I can put in my high interest account, and earn interest on it (along with additional savings, so that I have some overhead in case I calculated wrongly). Then, on 15th of May (nearly 16 months after my first salary), I can take it out of the high interest account and pay it to the Tax Administration.
According to my calculations, I could earn as much as 9000 NOK in interest a year this way. It seems foolish to me to forfeit this interest to the Tax Administration when I do not have to.
What are the downsides to this approach?