When and how is the fee paid?

The same fee can be due at different moments: on signing, on filing, when the benefit arrives, or in stages. A fee due on filing is paid before the tax authority has looked at the claim. A fee due on receipt is paid from the benefit. A fee paid in stages spreads the cost but may mean paying for work on a claim that is later withdrawn. The timing also decides what happens if the benefit arrives as a reduction in tax rather than cash, or arrives in parts.

A payment schedule in the letter: what is due, when, and against what. For a fee on receipt, a definition of receipt that covers cash, tax reductions and partial payments. For a fee on filing, a statement of what happens if the claim is later reduced. For staged payments, what each stage buys.

A fee due in full before filing. "Payable on completion" with completion undefined. Interest or uplifts for late payment that start before the benefit could have arrived. Payment terms in a separate document you have not seen.

• The clause: fee basis
• The script: asking how the fee is calculated
• Red flag: unclear fee base. Green flag: a fee you can work out yourself
• Deferred fees and percentage of refund fees