The alvará and the certificado are the two forms of construction licences that the IMPIC issues to companies working in construction in Portugal.
What it is
The IMPIC (the public body that licenses construction companies) issues two types of construction licence. The alvará is the full licence. It is divided into classes, and each class sets the maximum contract value a company may take on, from small classes for lower-value work up to the highest class for very large projects.
The certificado is a lighter licence for small works, up to a lower value limit that is set in the applicable rules and excludes VAT. It does not use the same class system as the alvará. Check the current limit with the IMPIC, because monetary limits can be updated.
Who needs it
Any company acting as a construction subcontractor in Portugal needs one of these two licences, whichever fits the work. This applies to Portuguese companies and, in most cases, to foreign companies as well. Which licence, and which class, depends on the value of the work the company actually carries out under each (sub)contract, and the licence's category and subcategory must match the type of work.
Comparing values alone is not enough, and the size of the company itself does not decide it.
How long it is valid
Both the alvará and the certificado are valid for an indefinite period in principle. There is no fixed expiry date printed on the document. However, the licence is reviewed by the IMPIC every year, and an annual fee is due for that review. If the fee is not paid on time, the licence can be cancelled; the IMPIC describes a procedure for remedying a late payment, so check the licence's actual status instead of assuming. The licence can also be suspended for other reasons, such as a lapsed work-accident insurance policy or unresolved tax debt.
What to watch out for
A paper copy of the alvará or certificado says very little about whether the licence is still valid today. Because status can change without a new document being issued, only the IMPIC's public online register shows the current, real status of a licence. A printed certificate from last year may already be worthless, even if it looks perfectly official.
A licence can be cancelled or suspended without any new paper being issued. Always check the current status in the IMPIC's public register rather than trusting an old copy.