多退少补

refund for any overpayment and supplementary payment for any underpayment

多退少补duō tuì shǎo bǔ

退掉事先多收的部分，补交事先少交的部分。return the overcharge and demand payment of the shortage, The balances will be paid to either side as the case may be.

多退少补duō tuì shǎo bǔ

交多了，多的部分退回；交少了，少的部分再予补足。