What do the VAT categories stand for e.g. RCS, RCGR, RCSR, OOS etc?

Hi @james-wolsey-ski,

I'm here to help you with your query. 

RCS - It's a Reverse Charge applied at the standard rate for Services bought from suppliers in the EU.

RCG - It's a Reverse Charge applied at the standard rate for Goods bought from suppliers in the EU. 

More information about the VAT codes you provided is in this article: Temporary VAT rate reduction due to Covid-19. It has the steps on how you can review your transaction to ensure they reflect the temporarily reduce rate.

Feel free to tag me in the comments below if you have other questions. I'll get back to you as soon as I can.