Electronic invoicing for accountants: automating client flows via API

Electronic invoicing for accountants is still, in 2026, one of the most critical processes for professional firms and advisors managing multiple VAT-registered entities. Every day, documents must be downloaded, data verified, transactions reconciled, and all information kept updated and available in accounting systems.

However, as the number of clients grows, manual management risks slowing down the firm's operations. Repeated access to portals, manual downloads, and constant checks consume time that could be spent on higher-value activities.

For this reason, more and more firms are choosing to automate electronic invoicing through APIs integrated with their management software. The goal is not only to save time but to build more reliable, scalable workflows ready to support the firm's growth.

Why automate electronic invoicing for accountants

Electronic invoicing for accountants today requires a much higher level of organisation than in the past. The increasing volume of documents and the need to work on multiple clients simultaneously make daily operational management increasingly complex.

Many firms continue to use manual procedures to access the Tax Drawer (Cassetto Fiscale), download invoices, and feed their accounting software. This approach may work with low volumes, but it quickly shows its limits as companies, documents, and deadlines increase.

For professional firms, automation represents above all a change in the operating model: less time spent on document collection and more focus on control, advisory, and strategic support activities for clients.

When managing multiple electronic invoices becomes a problem

Managing multiple electronic invoices represents one of the main pain points for accounting firms and tax consultants. Indeed, every client has their own document flows, deadlines, and specific operational requirements.

When the number of VAT numbers increases, even seemingly simple activities can turn into a bottleneck. 

Think, for example, of the monthly or quarterly closing: dozens of logins to portals, missing documents to retrieve, invoices to reconcile, and continuous customer queries on the status of registrations. In these situations, manual management risks absorbing most of the firm's working hours.

Consequently, electronic invoicing for accountants requires tools capable of centralising and automating processes.

Operational limitations of manual download from the Tax Drawer

Manually consulting the Revenue Agency (Agenzia delle Entrate) portal involves a series of repetitive operations. It is necessary to log in, select the search criteria, start the download requests, and wait for the files to be processed.

Furthermore, the procedure must often be repeated several times to download different types of documents or distinct time ranges. For this reason, in electronic invoicing for accountants, manual downloading risks significantly slowing down the entire workflow.

How the Tax Drawer works for accounting firms and accountants

In the electronic invoicing process for accountants, the Tax Drawer represents the access point to clients' tax information.

Through the service provided by the Agenzia delle Entrate, businesses and professionals can consult documents, registration details, and information related to their activity. However, when there are numerous clients to manage, manual access to the portal becomes increasingly inefficient.

The ability to automatically integrate this data into one's own systems therefore represents an important opportunity for optimisation.

Which documents can accountants and intermediaries consult

Electronic invoicing for accountants authorises access to various types of documents within the Tax Drawer. These include:

• issued electronic invoices;

• received electronic invoices;

• F24 payment forms;

• taxpayer's registration and tax data.

Having this information automatically available helps speed up checks, reconciliations, and administrative activities.

Proxy delegation and authorization: the prerequisite for accessing client data

To automate electronic invoicing for accountants, the client must grant a valid proxy delegation or authorization. Access to data in the Tax Drawer can only take place within an authorization perimeter defined by the Revenue Agency.

Before enabling any integration, it is therefore essential to verify that proxy delegations and authorizations are correctly configured.

Multi-client electronic invoicing API: how to automate workflows

Multi-client electronic invoicing APIs make it possible to transform repetitive tasks into automated processes.

Through an API integration, the firm can periodically retrieve documents from the Tax Drawer without having to log in manually to the Revenue Agency portal. In this way, electronic invoicing for accountants becomes a continuous, integrated workflow perfectly aligned with the systems already in use.

From an operational point of view, the API model allows for scheduling the download of documents according to pre-defined intervals, for example once or more times a day. The retrieved files can be automatically routed to ERPs, accounting software, or digital archiving platforms, without manual exports or intermediate uploads.

How the bulk download of client invoices works

The bulk download of client invoices allows for the automatic retrieval of tax documents associated with the various VAT-registered clients managed by the firm. The API developed by A-Cube allows you to schedule periodic and automated downloads, avoiding daily manual tasks.

Once retrieved, documents can be made immediately available in the firm's management software, improving operational continuity and reducing processing times. We have discussed this in depth here.

Manual management vs automated flow

Automatic synchronisation of the Tax Drawer via API

Automatic synchronisation of the tax drawer allows internal systems to be kept constantly up to date without manual intervention.

Through API integration, documents are retrieved according to planned schedules and transferred directly into ERPs, accounting software, or administrative platforms. This approach reduces errors, oversights, and repetitive tasks, ensuring data is always updated and ready for subsequent processing.

To learn more, you can read our complete guide in this article.

Integrating ERP and electronic invoicing software for accounting firms

One of the main advantages of automation relates to the ability to integrate electronic invoicing for accountants with the tools already used within the firm. APIs allow for easily connecting ERP, CRM, and accounting software, eliminating manual file export and import steps.

The result is a more efficient and perfectly integrated document ecosystem.

Data immediately available in management systems

For many firms, the real benefit of automation does not lie in simply downloading invoices, but in the ability to immediately use that data in subsequent processes. Once imported into the software, the documents can feed accounting entries, reconciliation procedures, VAT checks, and reporting without further manual steps.

This approach reduces processing times and allows for a more up-to-date view of the clients' financial status, especially during periods marked by high volumes of documents.

A scalable infrastructure to manage more VAT numbers

Electronic invoicing for accountants must be able to grow along with the firm.

An API infrastructure allows for managing both a few businesses and thousands of clients without modifying the operating model. Scalability is therefore an essential element for all firms looking to expand their business.

Security, controls, and business continuity in workflow automation

When electronic invoicing for accountants is automated, security and reliability assume a key role. Every access must take place in compliance with the authorizations granted by clients, and all operations must be correctly tracked.

Additionally, it is important to provide monitoring and contingency management tools to ensure business continuity.

How to reduce errors and disruptions in automated processes

Among the most frequent errors are missing delegations, expired credentials, and temporary downtime of Revenue Agency services.

For this reason, the A-Cube API integrates alert and monitoring systems that allow for the quick identification of potential issues. For instance, notifications are sent when access passwords are about to expire, preventing sudden service disruptions.

Automating electronic invoicing for accountants with A-Cube APIs

Automating electronic invoicing for accountants means building more efficient processes, reducing manual tasks, and improving data quality.

A-Cube's bulk download from the Tax Drawer API allows you to automatically download electronic invoices of clients, integrate them with the systems already in use, and manage high volumes easily and securely.

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