There is a word for it. It's a percentage of the cost of the contract withheld by the public authority to cover debts or defects. I can't find a PR source that explicitly defines it, but this, from the PR government contracting regulations, gives us some idea (it's from the Google cached version; the doc. itself won't open for me):

"Retención del diez por ciento (10%) de la cantidad a pagarse por cada fase del proyecto, hasta alcanzar el cincuenta por ciento (50%) de obra ejecutada; luego de lo cual se reducirá el retenido a cinco por ciento (5%). El monto total del retenido se liquidará al finalizar la construcción, previo a ser certificada como correcta por el Director Ejecutivo o su representante autorizado."
https://webcache.googleusercontent.com/search?q=cache:JiYGyt...

"Retainage on public works
[...]
“Retainage” means the part of a public works contract payment withheld by a governmental entity to secure performance of the contract (V.A.C.S. Art. 6252-5b, Sec. (1.)"
https://wtagc.org/retainage/

"Contracts may include a provision that allows one party to withhold a certain percentage of the total payment called for under the contract until a project is substantially complete; the amount withheld is commonly referred to as a retainage. Retainages are intended to address concerns that a contractor will not finish a project if full payment already has been made. Retainages are frequently provided in construction and manufacturing contracts, as well as in contractual arrangements with the U.S. government."
https://www.thetaxadviser.com/issues/2013/jul/clinic-story-1...

"On public works contracts in Washington State, public agencies are required to withhold 5% of each progress payment as Retainage. The Retainage is a trust fund for the protection of the Washington State Department of Revenue for unpaid taxes and for workers, subcontractors, and suppliers who have not been paid."
http://publiccontracting.blogspot.com/2008/06/calculating-re...

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Note added at 3 hrs (2019-01-13 17:08:45 GMT)
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A translation is not evidence, but here, for what it's worth, is an extract from the English version of Puerto Rican public works contract (for the Puerto Rico Infrastructure Financing Authority):

"PRIFA reserves the right to request from Contractor any document it deems necessary in order to process any Application for Payment, including the retainage.
3.1.3 In accordance with the Contract Documents, the amount of retainage with respect to progress payments is ten percent (10%) of each partial payments [sic] made to the Contractor."
http://periodismoinvestigativo.com/wp-content/uploads/2016/0...