INTRODUCTION 3 can change depending on the context in which it is used. As an artifact of the communication channel, not all documents are born digitally, and the quality of the document can vary greatly, with some documents being handwritten, scanned with low resolution, or even a picture of a document. Furthermore, documents are often not standardized templates and can be highly variable in terms of layout, structure, and content. Finally, the longer the document, the more computationally demanding it becomes to process, and the more likely it is to induce errors, which can be harder to detect. Addressing the inherent challenges of document processing, and achieving high levels of accuracy, processing speed, reliability, robustness, and scalability in DU forms the applied scope of this thesis. (II) Consider the example given of the birth certificate. While I might not appreciate as much the manual handling of this document, if they had registered my baby girl’s name (Feliz, Spanish writing without an accent on the ‘e’) incorrectly, I would be pretty upset as this could have further repercussions. Whereas this error might be easily rectified, it is not so easy to do so in the case of a mortgage application, where the wrong information could lead to a rejection of the application, or even worse, a loan agreement with the wrong terms and conditions. This demonstrates that, even when full automation of document processing is in high demand, it is not always desirable if the risk of failure might be too large. Nevertheless, a lot of the potential for automation remains untapped, and organizations are increasingly looking for solutions to fully automate their document processing workflows. However, full automation, implying perfect recognition of document categories and impeccable information extraction is an unattainable goal with the current state of technology [79]. The more realistic objective set is Intelligent Automation (IA) (elaborated on in Section 2.4), where the goal is to have the machine estimate confidence in its predictions, deriving business value with as high as possible volumes of perfect predictions (Straight-Through-Processing, STP) without incurring extra costs (False Positives, FP). The leitmotif of this thesis will be the fundamental enablers of IA: confidence estimation and failure prediction. Calibrated uncertainty estimation with efficient and effective DU technology will allow organizations to confidently automate their document processing workflow, while keeping a human in the loop only for predictions with a higher likelihood of being wrong. To date, however, little research has addressed the question of how to make DU technology more reliable, as is illustrated in a toy analysis (Table 1.1) reporting the absence of many IA-related keywords in the Proceedings of the 2021 International Conference on Document Analysis and