ContaPlus to Contasol Migration: Guide for Accountancy Firms

If you have been working with ContaPlus —now rebranded as Sage 50— and are evaluating the switch to Contasol, you are not alone. Since Sage redesigned its licensing policy and raised maintenance costs, hundreds of accountancy firms and professional offices across Spain have made the transition to Contasol, the professional accounting solution from the TeamSystem/DELSOL group. This article explains what the migration involves, what data you can carry over, how to plan the change without disrupting your clients' service, and what advantages you gain in view of the upcoming Verifactu obligation.

Why accountancy firms are leaving ContaPlus/Sage 50

ContaPlus was born in the 1990s as one of the first accounting programs for Spanish SMEs. For decades it was the de facto standard in many firms. However, its integration into the Sage portfolio brought a subscription model that many users consider expensive relative to the actual features offered, especially in firms managing a medium-to-high number of companies.

The most frequent reasons we hear at Summum Sistemas when analysing each case are three:

• Rising subscription costs without noticeable functional improvements for the firm's day-to-day work.
• Outdated file architecture that complicates network collaboration and remote access.
• Uncertainty around Verifactu: firms want to be sure that whichever software they choose is already adapted or will be in time before January 2027 for legal entities and July 2027 for sole traders.

Contasol addresses all three points: its price is substantially lower (with a free 30-day trial, no commitment required), its architecture supports network working and a cloud mode with Contasol Cloud, and the TeamSystem/DELSOL group already has an SII module integrated —incompatible with Verifactu for companies already on SII, but ready for those that are not— and is working on the Verifactu adaptation of the suite.

What is Contasol and who develops it

Contasol is the professional accounting module of Software del Sol (DELSOL), a company based in Mengíbar (Jaén) acquired by the Italian group TeamSystem in February 2021. TeamSystem is the largest SME management software group in Italy, with more than 3.1 million clients in Europe and turnover exceeding 1,150 million euros in 2025.

Contasol covers the full accounting cycle: manual and automatic journal entries, VAT returns (303, 390, 349), personal income tax (130, 131), corporate income tax (200), annual accounts in accordance with the Spanish General Chart of Accounts, and the Immediate Supply of Information (SII) for companies with annual turnover above 6 million euros. It is available in four versions:

Note: prices are indicative from the manufacturer and may vary. Always check the current rates at sdelsol.com.

At Summum Sistemas we are an Official TeamSystem Partner and we implement and migrate Contasol in accountancy firms and professional offices throughout Castilla y León and the Canary Islands. For full details of the service, visit our Contasol implementation and support page.

Key differences between ContaPlus/Sage 50 and Contasol

Before migrating it is worth understanding the similarities and differences between the two environments. Both work on the Spanish General Chart of Accounts and produce the same tax returns, but there are workflow differences that affect how long the team takes to adapt.

• Chart of accounts: Contasol uses the standard chart of accounts with the same numbering as ContaPlus. Adapting each company's customised chart of accounts is the most delicate step in the migration.
• Data files: ContaPlus/Sage 50 stores data in proprietary .con / .emp files. Contasol uses its own database. The intermediate export is usually done in ASCII or Excel format.
• Interface: Contasol has a short learning curve for ContaPlus users because the logic for journal entries, the day book and the ledger are equivalent. In the first few days users notice naming differences that disappear after a week of use.
• Integration with invoicing: Contasol integrates natively with Factusol (invoicing and stock), also from TeamSystem/DELSOL. If your firm also manages clients' invoicing, the DELSOL 360 suite combines both modules in the cloud.
• SII: Contasol includes the SII module. Sage 50 does too, but the configuration differs. When migrating, digital certificates and AEAT endpoints must be reconfigured.

Step by step: how to migrate from ContaPlus to Contasol

1. Inventory and preliminary closing

Before touching anything, make an inventory of the companies you manage in ContaPlus: number of companies, open financial years, periods with outstanding entries to balance, whether you use SII and for which financial years. Also define the cut-off point: the most common approach is to migrate at the start of the financial year (1 January) with the opening balances, without carrying over the full historical journal. If you need the history for reference, you can keep the old installation in read-only mode.

Extend the inventory with the exact version and edition of ContaPlus/Sage 50 installed, the data path, the modules each company uses (analytics, receivables/payables, fixed assets), its integrations with invoicing, payroll or banking, and who the functional and technical contact is if a question comes up during the project. Decide, company by company, what you actually need inside Contasol (almost always the chart of accounts, journal entries and opening balances) and what can stay in the historical archive in read-only mode: analytics and projects, documents and attachments, or financial years already closed and filed. «Migrating everything» is not a verifiable requirement: every block of information needs a retention period, a purpose and a way to check afterwards that it is still accessible.

Before taking the step, verify that the ContaPlus backup can actually be restored, not just that the backup file exists: a backup that has never been tested is not a backup. Also review the quality of the source data: unbalanced entries, duplicate sub-accounts, dates falling outside the financial year or badly typed tax IDs. Fix what you can before exporting. Whatever cannot be fixed in time should be documented as a known issue: migrating an error does not make it correct, and «cleaning up» an already-filed financial year without leaving a record of what changed and why is a bigger risk than leaving it as it is.

2. Exporting data from ContaPlus/Sage 50

Sage 50 allows you to export the chart of accounts and current-year journal entries in Excel or CSV format from the utilities menu. The minimum fields you need are: account code, description, debit, credit, date, concept and document number. Also export accumulated balances from previous financial years if you need them for future audits or tax inspections.

3. Preparing Contasol: companies and chart of accounts

In Contasol you create each company from scratch with its fiscal data (tax ID, address, VAT regime, financial year). You then import the chart of accounts from the exported Excel file. Contasol has an import wizard that maps columns; if your chart of accounts follows the standard chart, the mapping is nearly automatic. Customised sub-accounts (suppliers, clients, creditors) are also imported in bulk.

TeamSystem documents several official routes for this import in its help centre: through the ContaPlus option inside Utilities > Imports, by loading ContaPlus data files directly, or by importing certain data from Excel/OpenOffice. The exact route depends on the installed version, so it is worth checking the current help pages before running the process and not mixing instructions from a different version than your own.

Always run the first real import on a test company, ideally one with more quirks than average (several activities, different VAT rates, legacy sub-accounts) rather than the simplest one, and never on the live company. Log the date, who did it, the source and target versions, the backup used, any warnings or errors that appeared and the import counts. If something fails and the test needs repeating, do it on a clean company: importing twice over the same earlier attempt can duplicate entries and balances.

4. Importing opening balances

With the chart of accounts ready, you enter the opening balances (journal entry 0 of the financial year) from the closing balances of the previous year. This is the most critical step: always check that assets balance against liabilities before validating the opening entry. Contasol has a verification screen that alerts you if the opening entry is unbalanced.

5. Migrating current-year journal entries (if applicable)

If the migration takes place mid-year, the already-posted journal entries must also be transferred. In this case the import is more delicate: journal entry numbers must be preserved and the debit and credit totals must match period by period against ContaPlus statements. We recommend doing this company by company and validating the trial balance after each import.

6. Reconfiguring tax returns and SII

Each company needs its VAT rates, input and output VAT accounts, and —if applicable— the SII connection parameters (representative tax ID, digital certificate) configured. This phase takes between 15 and 45 minutes per company depending on complexity. At Summum Sistemas we handle this in our migration projects so that the firm's team does not lose time on technical configuration.

7. Team training and run-in period

The learning curve for an accountant who knows ContaPlus is short. In our experience, after a two-hour session the team is already working fluently in the new environment. We recommend a four-week run-in period during which support is available to resolve operational questions: keyboard shortcuts, generating tax returns, exporting reports.

8. Cut-off, rollback and data security

Before closing the project, put the cut-off point in writing: the exact date and time from which ContaPlus stops accepting new entries and Contasol becomes the active system. That cut-off includes the last backup, the final import of pending movements and the mandatory reconciliations before authorising Contasol to open in production.

Also decide, before you start rather than during the rehearsal, how far you can roll back if something goes wrong: once real entries have been posted in both systems at the same time, undoing the change can end up creating two different ledgers for the same company. The criterion for aborting the migration has to be set in advance, not improvised mid-cutover.

The copies you handle during the project contain data on clients, suppliers, staff and bank accounts: encrypt them, restrict who can access them and delete them from the working machine as soon as the migration is finished. If an external provider is involved, review the contract, remote access and the return or destruction of the data with them once the work is done. From day one, create individual Contasol users with minimum permissions: do not simply replicate the shared administrator account you may have used in ContaPlus.

What to do with analytics, fixed assets, receivables/payables and documents

These modules tend to take a back seat during migration and are the ones that generate the most issues afterwards, because the standard import does not always replicate every field or relationship. It is worth deciding, module by module, whether to migrate natively, load via template, transfer only the opening balance (leaving the rest in the historical archive) or rebuild it by hand:

• Fixed assets: reconcile acquisition cost, start date, accumulated depreciation and remaining useful life of each item.
• Receivables and payables: reconcile counterparty, due date, outstanding amount and status (paid, collected or overdue).
• Analytics: reconcile cost centres, projects and allocation keys.
• Documents and attachments: scanned invoices and supporting documents do not always travel with the entry during import. Decide in advance whether they stay inside Contasol or in a separate repository, and use a common identifier so each document can be linked back to its entry.

Traceability across the whole process needs to be able to answer four questions at any time: which system the data came from, when it was imported, what transformation it went through and who signed it off.

Contasol and Verifactu: what you need to know before 2027

One of the reasons this is a particularly relevant moment to migrate is the upcoming Verifactu obligation, regulated by Royal Decree 1007/2023 as amended by RDL 15/2025. The current deadlines are:

• Legal entities: mandatory compliance from 1 January 2027.
• Sole traders: mandatory compliance from 1 July 2027.

It is important to clarify a point that often causes confusion: there is no «homologation» of software by the AEAT. The legal mechanism is the manufacturer's declaration of conformity under RD 1007/2023. The manufacturer declares that its software meets the technical requirements; there is no official list of «certified» software nor a prior approval process from the Tax Agency.

It is also worth knowing that SII and Verifactu are mutually exclusive: companies already required to use SII (annual turnover above 6 million euros) will not have to adopt Verifactu. For all others, the invoicing software —Factusol, Billin and the Aplifisa suite of FactuGes— already has the adaptation under way. Contasol, as accounting software rather than invoicing software, is not directly affected by Verifactu, but the integration with whichever invoicing module you use is.

If your firm also handles client invoicing with Factusol, moving to the DELSOL 360 suite (Factusol + Contasol + Nominasol in the cloud) gives you a clear, single roadmap to comply with all tax regulations before the deadlines. Full details are on our Contasol service page.

How long does the migration take

It depends on the number of companies and the state of the accounts. As a rough guide:

• Firm with 10–30 companies: between 3 and 5 days of technical work spread over two weeks (to avoid cutting daily operations).
• Firm with 30–100 companies: between 2 and 4 weeks, with batch imports and validation by groups.
• Firms with more than 100 companies: bespoke projects; typically done in waves over a full quarter.

The factor that extends the migration most is not the technical import but the balance verification: reconciling company by company, detecting unbalanced entries or incorrectly mapped sub-accounts. That is why it is essential to carry out the migration with a proper methodology rather than in an improvised way.

Regardless of size, the project always goes through the same phases: diagnosis and inventory, a pilot import on a test company, correcting mappings and configuration, a timed full-cutover rehearsal and, finally, going live with reinforced support during the first few weeks. Skipping a phase to move faster usually costs more time than it saves.

How to check the migration has been done properly

An import finishing without error messages does not mean the migration has been done properly: it only means the technical process was not interrupted. The only reliable way to accept it is to compare specific figures between ContaPlus and Contasol, company by company:

• Number of entries per financial year and period.
• Debit and credit totals, and that they still balance.
• Balance sheet figures per sub-account.
• Profit and loss amounts per account.
• VAT and withholding tax bases, rates and amounts.
• Opening and closing entries and balances, linked to each other.
• Outstanding, collected and paid due dates.

When a difference appears, classify it: data not supported by Contasol, a configuration error, an error already present at source, rounding, an unintended filter, or an import fault. Record the decision taken in each case. Before closing the project, it is worth going through a checklist like this:

• ContaPlus backups verified and readable.
• Pilot import documented, with date, source and target versions, and counts.
• Entry counts and debit/credit totals reconciled.
• Balance sheet, profit and loss and taxes compared.
• Analytics, receivables/payables and fixed assets reviewed.
• Attachments and history accessible.
• Users and permissions configured in Contasol.
• Cut-off and rollback rehearsed in a prior drill.
• Acceptance signed off by the person responsible for the accounts.

Common mistakes when migrating from ContaPlus to Contasol

Most of the issues we see in migrations come not from Contasol or ContaPlus, but from shortcuts taken in the process itself:

1. Importing without first testing that the backup can be restored.
2. Treating the migration as fine simply because no error message appeared.
3. Comparing only the total balance rather than the figures per account, tax or module.
4. Repeating the import on a company that was already imported into, instead of starting from a clean one.
5. Forgetting attachments, analytics, receivables/payables or fixed assets by focusing only on entries and balances.
6. Not keeping a readable copy of ContaPlus once migrated.
7. Changing the length or structure of the chart of accounts without a documented mapping.
8. Working with both systems open at once past the cut-off point.
9. Not having taxes and books validated by whoever is responsible for tax advice.
10. Deleting backups too soon, before the agreed warranty period ends.

Advantages of migrating now rather than waiting

The sooner the migration is done, the more time the firm's team has to work with the new software before the busiest tax periods (April for corporation tax, July for income tax). Migrating in January is ideal; doing it in March or April, with tax returns looming, multiplies the risk of errors. Migrating now also gives time to resolve any issues without pressure and to take advantage of the integration with the DELSOL 360 suite if you later want to unify invoicing, accounting and payroll in a single cloud environment.

At Summum Sistemas we have been accompanying companies and professional offices in management software implementations and migrations since 2017, with offices in Valladolid and Las Palmas de Gran Canaria and service points by appointment in Burgos, Palencia and Aranda de Duero. The team that assists you knows Contasol in depth and has managed migrations from ContaPlus, a3ASESOR and Sage Despachos.

Frequently asked questions

Can I migrate only the opening balances or also the full journal history?

Both options are possible. Migrating opening balances is the fastest and the one we recommend in most cases: the firm starts the new financial year in Contasol with clean balances and keeps read-only access to ContaPlus for historical queries. Migrating the full journal makes sense when the firm needs to work with current-year entries in Contasol without relying on the previous program.

Is data lost when exporting from ContaPlus to Contasol?

If the export and import are done with the correct methodology, no relevant information is lost. The chart of accounts, balances, journal entries and company data are transferred in full. What is not migrated are ContaPlus screen configurations or custom reports, which must be recreated in Contasol. Historical tax data (submitted returns) remain in ContaPlus; there is no need to migrate them because you will have kept them as PDFs or in the AEAT system.

Does Contasol work on a network for several simultaneous users?

Yes. The Standard and Elite versions support local network working with multiple simultaneous users. The Cloud version (Contasol Cloud) is accessible from any browser and removes the need for a local server: several staff members can work at the same time from different locations. This option is especially useful for firms with remote working or multiple offices.

What happens with SII if my clients are already registered?

When migrating to Contasol, you must reconfigure the SII parameters for each already-registered company: digital certificate, representative tax ID (where the firm acts as representative) and the VAT accounting accounts. Invoice records already submitted to the AEAT's SII do not need to be resubmitted; only new entries from the migration date onwards are affected. We also recommend reading our article on Contasol and SII for more detail on the technical configuration.

Can I repeat the import if something goes wrong?

Yes, but always on a clean company, never on top of an earlier attempt: repeating the import over data already imported can duplicate entries and balances. That is why we recommend rehearsing first on a test company, ideally one with more quirks than average rather than the simplest one, before touching the live company.