Can minority shareholders in a Portuguese Lda force access to board minutes and accounts?

The situation you describe—managers refusing to share minutes, contracts, and accounts with a 15% shareholder—is a clear case where Portuguese law is squarely on your side.

The Commercial Companies Code grants shareholders robust information rights. Under Article 214º, any shareholder may request information on company affairs. More significantly for your position, Article 215º gives shareholders holding at least 10% of share capital the right to demand written information on management matters and to examine the company's books and records directly—or through an accountant of your choosing. You comfortably exceed that threshold.

If management continues to stonewall, Article 216º provides for a judicial inquiry to compel disclosure. Courts take these requests seriously, particularly where there are indications of opacity in governance.

As for challenging decisions already taken: resolutions that breach the articles of association or proper procedure may be annulled under Article 58º, though you would need to act within 30 days of becoming aware of the resolution. Resolutions violating mandatory legal provisions are null outright under Article 56º—no time limit applies.

The related-party transactions you mention are concerning. If managers have been directing business to themselves or connected parties at the company's expense, this constitutes a breach of fiduciary duty. Liability actions against managers for damages to the company are available, and the evidentiary trail often emerges precisely through the information requests I mentioned above.

Recommendation: send a formal written demand to management—registered post, acknowledgment of receipt—citing Articles 214º and 215º and requesting access to minutes, accounts, and all relevant contracts. Give them 15 days. If they refuse or simply ignore you, move to the judicial inquiry and assess what grounds exist to challenge irregular resolutions.