# legal.retainer-drawdown Money a client pays on account of costs is held in client account until a bill is delivered; then it may be transferred to pay that bill. This applies the money on account to the bills in the order given, each bill taking as much as it can until the money runs out, and reports what each bill took, what each still has due and what is left on account. Everything is in exact minor units: the applied and outstanding amounts of a bill always add to the bill, and the total applied plus the balance is always the money on account. The order is the caller's: pass the bills oldest first to pay them in the order they were delivered, which is the usual term in a client care letter. A bill of zero is allowed and takes nothing. A negative bill (a credit note) is an error: credit notes reduce a bill before this step, they do not add money to the account. This is arithmetic only. Whether money may be taken at all is a regulatory question. Rule 4.3 of the SRA Accounts Rules (https://www.sra.org.uk/solicitors/standards-regulations/accounts-rules/) requires a bill of costs or other written notification of the costs to be given before client money is transferred to pay them, and the payment to be for the specific sum identified and covered by the money held for that client. Pass only bills that have been delivered, for one client and matter. Whether the last bill may be part-paid from what is left, as this does, or must wait until the whole sum is held, is a question for the firm's compliance officer (COFA); check `outstanding` on each bill and transfer nothing for a part-paid one if your firm reads the rule strictly. All amounts must be in one currency.