Why is GDAX charging maker's fee when using API?

Question

Why are we getting charged maker's fee when creating buy orders on the GDAX API.

For example I deposited 100 EUR to GDAX account and wanted to place a limit buying order for size 0.5 ETH at the price of 200 EUR and received HTTP 400: "Insufficient funds" as a response.

I lowered the size to 0.4 and the order went through, but I was left with 19.80 EUR on my account - meaning that 0.25% was taken as well, but my order was at 200 EUR and 0.4 ETH, totaling 80 EUR not 80.2 EUR.

Looking at the API there shouldn't be a maker's fee.

Has anyone else noticed this?

Doing it manually in the GUI I am left with 20 EUR.

Answer 1

There is no maker fee using API, but when place new order, the default parameter for "post_only" is false, which means it is possible set a price to become a taker, hence GDAX will make sure you have enough funds to cover the fees.

Set post_only to true then GDAX will allow you to spend your entire account without reserves for fees.

Answer 2

I'm not sure exactly why this would happen, but according to the SEC:

"If an execution occurs, the liquidity providing “maker” receives a rebate, and the “taker” that executes against that resting order pays a fee to the market."

This means the maker is the one who already had their trade order in the books, and the taker is the one who places the order and who's order is executed immediately against the makers.

Using the API, you could've accidentally placed a buy order below or at the current price or ETH. If this happened you would be charged a "taker" fee instead of the 0% maker fee. That is my only explanation, because it says here in there API docs there is zero maker fee.

If you were the maker but charged the taker fee, I'd ask GDAX why this is occurring here

Answer 3

If you go to the fills tab you can see which order(s) your order was matched with. You can also see if your order was executed as a maker or a taker. It likely executed as a taker, which is why you had to pay the fee.