This Practice Note looks at the mechanism of set-off in the context of construction where it is often used, in building contracts and sub-contracts, to manage cash flow (by offsetting opposing financial claims). It examines the types of set-off (legal, equitable, insolvency and contractual), how set-off works in practice and the distinction with abatement. It also offers practical tips regarding set-of (and the exclusion of set-off) in construction contracts, and considers the effect of the HGCRA 1996 on the use of set-off.