Payment
Late-payment interest and recovery costs
This is your leverage when a client drags out payment. Even if the contract says nothing, UK law lets a business charge interest and a fixed fee on late commercial invoices, so a clause that tries to strip that away is worth pushing back on. Spelling out the interest right in the contract makes it easy to invoke without an argument.
What to look for
Whether the contract gives you a right to charge interest and a fixed sum for recovery costs when the client pays late, and at what rate. Also check the contract does not try to waive or reduce your statutory rights below a meaningful remedy.
How Clause rates it
Wording you can ask for
If any sum is not paid by its due date, interest shall accrue daily on the overdue amount at 8% per year above the Bank of England base rate until paid, and the Client shall reimburse the reasonable costs of recovering the debt.
The UK angle
The Late Payment of Commercial Debts (Interest) Act 1998 sets statutory interest at 8% above the Bank of England base rate and fixed compensation of £40 (debts under £1,000), £70 (£1,000-£9,999.99) or £100 (£10,000+) per invoice; these apply automatically to business-to-business debts and a contract term must give a 'substantial remedy' to displace them.
See this on your own contract.
Paste your contract and watch these rules light up your own clauses.