noun, の adjective
The remaining surplus is the remainder or residual left over.
Just bear in mind that this is a technical word that you'll mostly see in legal and financial contexts.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
After bankruptcy, any remaining assets will be distributed.
"Have you guys discussed the residual risks, too?" "Not yet. We all forgot the formula to calculate residual risk, so we can't have the discussion."
What is the this month’s remaining balance as of now?