Thomson Reuters ONESOURCE

Thomson Reuters ONESOURCE is an enterprise tax management platform covering global tax compliance, tax provision under ASC 740, transfer pricing, and indirect tax, deployed modularly on a shared data foundation.

How accounting firms use it

Large firms use it when serving multinational clients whose tax data spans many entities, currencies, and reporting frameworks. The provision module is usually the entry point: calculating consolidated income tax expense for financial reporting under a hard close deadline, with the result subject to audit.

The reason it exists as a category is that spreadsheet-based provision at this scale is a control weakness. Version control, formula integrity, and reviewability all degrade as entity counts rise, and auditors increasingly treat that as a deficiency rather than an inconvenience. A platform with audit-ready workpapers and a controlled calculation path addresses the finding directly.

Key features

Tax provision automates current and deferred tax calculation, valuation allowances, and uncertain tax positions with multi-GAAP support and currency translation, producing workpapers that tie to the reported figures.

Compliance modules handle statutory reporting across jurisdictions. Transfer pricing supports documentation and country-by-country reporting. Indirect tax, property tax, and trade and customs are available as separate modules.

Integration with SAP and Oracle sources data directly from the ERP, and Checkpoint links research into the workflow.

Who it’s best for

Big Four and large regional firms, and in-house corporate tax departments at multinational companies — organisations where entity count and jurisdictional spread make manual approaches untenable.

Small and mid-sized practices are well outside the intended range and should use UltraTax CS, GoSystem Tax RS, CCH Axcess Tax, or Lacerte for domestic work.