Are liquidated damages enforceable?

Usually yes. Liquidated damages, often shortened to LDs, are a fixed sum, normally set per day or per week, that the contract says you must pay if you finish late, agreed in advance so nobody has to prove the actual loss. The courts will normally hold the parties to that figure. Under the leading modern cases the test is not whether the rate is a genuine advance estimate of the likely loss, but whether it is out of all proportion to any legitimate interest the employer, the party paying for the work, has in the job finishing on time, and that is a high bar, so most rates stand. The agreed rate applies whether the real loss turns out higher or lower, which can cut in your favour as well as against you. Two checks before signing: make sure the rate and any overall cap are clearly stated and the arithmetic works, and remember that deleting the clause does not delete your liability for finishing late, it usually just replaces a known, capped number with unliquidated damages, an open ended claim for whatever loss the other side can prove.

Say a housing contractor signs up to liquidated damages of £2,000 per week for late completion, and finishes six weeks late. That is £12,000, and even though the employer's actual loss turns out smaller, the fixed rate still applies, so the number is known and capped. Now imagine they had instead insisted the clause be struck out, thinking that removes the risk. It does not: lateness still breaches the contract, so the employer can now claim unliquidated damages, whatever late completion genuinely cost them, which on a housing scheme with knock on sales and finance could run well past 12,000. The clause they feared was often the friendlier of the two, turning an open ended exposure into a number they could see in advance.