I'm installing new outlets in my garage with each having their own breaker. My issue is that my neutral bus bar is full (except 1 slot). Can I combine all the neutrals together and utilize the 1 remainig neutral slot? i.e. twist the 4 neutrals together and use a single neutral to the bus?

You can buy buss extensions at HD or Lowe's.

It is a NEC code violation to have more than one Neutral conductor in one hole!

As ma0641 stated above. You can purchase Neutral bar extensions just about any hardware store.

A word of safety, if you don't know what you are doing, Please hire an electrician, It is much cheaper than a hospital stay or a funeral!

Neutral bars are pretty rare to add on. It is a ground bar that is usually added on. You cannot put neutrals on a bar that is screwed to the back of the panel.

If this is a main panel you can either double up on grounds of the same size, or add on a ground bar and move some grounds there.
You cannot double up on neutrals though.

Stan

I stand corrected, thank you. I did searches at Lowe's and Home Depot websites.

I found 1 (one) "Neutral Bus Bar extension kit". It is made by Schneider for a specific panel board. It had an insulating sheet, two plastic stand offs and the bar itself.

So, what I have been seeing must be Ground bus bar extensions incorrectly used as Neutral bar extensions. I checked the time bomb I have for a panelboard and sure enough there are 2 such extensions.

Tic -Tic! I better find some money and swap that panel out unfortunately, Social Security doesn't overpay us.