In a complaint under Section 138 of the Negotiable Instruments Act (NIA), the filing of additional documents generally depends on the stage of the proceedings and the discretion of the court. Typically, during the trial, parties are allowed to submit evidence and documents to substantiate their claims or defenses.

However, once the trial concludes and a judgment is delivered, the scope for submitting additional documents becomes limited, and such submissions may require permission from the court or may be considered only in exceptional circumstances.

In the context of the provided case, the court considered various documents, including the partnership deed and bank statements, during the trial, which indicates that documentary evidence is integral to establishing the facts of the case (!) (!) .

Therefore, while additional documents can generally be filed during the trial phase to support a complaint under Section 138, their acceptance after the conclusion of the trial or after a judgment is at the discretion of the court, often requiring a formal application or leave of the court.

In summary, additional documents can be filed in a complaint under Section 138 of NIA primarily during the trial stage, subject to the court's approval, and are less likely to be admitted once the trial has concluded unless exceptional circumstances justify their consideration.