This is a sensitive topic for architect and client. Fees are usually based on a percentage of the construction cost, an hourly rate or, more rarely, a fixed fee. Particular concerns arise regarding the steps an architect can take if the client fails to pay sums due. Some architects refuse to release drawings or threaten to withdraw planning applications. Other problems revolve around whether the architect is entitled to additional fees in certain circumstances such as dealing with claims, redesigning to reduce costs or simply because the contractor is taking longer to carry out the Works. Sometimes it is difficult to discover the true identity of the client, particularly where multiple limited companies are involved.