Key takeaways
- Co-sourcing lets large enterprises keep strategic control while using specialist providers for high-volume, multi-country compliance
- A simple activity map, from strategic to transactional and from high-risk to repeatable, shows what to keep in-house and what to shift out
- Clear SLAs and outcome-based KPIs make tax compliance outsourcing measurable and transparent
- Strong controls, documentation, and digital audit trails keep auditors, regulators, and internal stakeholders aligned
- Phased rollout, clear roles, and steady governance help your team move to the new model without chaos at quarter end
Building a Future-ready Tax Compliance Model
Co-sourced tax compliance is simple at its core. Your internal tax team keeps control of strategy and risk, while a specialist provider runs repeatable work on a shared platform. Instead of choosing between fully in-house and fully outsourced, you blend the two into one coordinated operating model.
This matters because indirect tax is changing fast. New e-invoicing mandates, near-real-time reporting, and new EPR rules arrive with little warning. At the same time, it is hard to hire and keep experienced indirect tax people, and boards want fewer surprises, cleaner audits, and better cost control. A co-sourced model gives you flexibility, scale, and automation without giving up ownership of decisions.
In this article we walk through how to decide what to outsource versus retain, how to set SLAs and KPIs, which controls you need for auditability, and how to manage a multi-year transition with limited disruption to the business.
Mapping Your Tax Compliance Value Chain
To design a co-sourced model, start with your indirect tax lifecycle. Break the work into clear steps so you can see what really happens each month and quarter. Typical activities include:
- Monitoring regulatory change and interpreting new rules
- Tax determination and configuration in ERP, billing, and marketplaces
- Data extraction, transformation, and enrichment
- Compliance calculations, checks, and validations
- Filings and payments in each country or state
- Reconciliations with GL, subledgers, and external reports
- Audit and controversy support when questions come from authorities
Now look at each activity on two axes:
- Strategic vs transactional
- High-risk vs repeatable
Items that are judgment-heavy or closely tied to your risk appetite usually stay in-house. That includes tax policy, deciding materiality thresholds, and managing disputes with authorities. These rely on deep knowledge of your business model, customers, and long-term plans.
On the other side, repeatable, data-heavy tasks are strong candidates for outsourcing or automation. Think monthly VAT returns, sales tax returns, EPR reports, and the data work that feeds them. These follow rules, happen on a schedule, and scale better on a global SaaS platform.
Cross-border work adds another layer. You may be dealing with:
- VAT across many EU countries and the UK
- Sales and use tax across US states
- EPR rules for packaging, electronics, or other products
A global platform can give you standardized workflows with room for local nuance. That way, your team sees one operating model, not a different spreadsheet and process for every market.
Choosing What to Outsource and What to Retain
Once the value chain is clear, you can decide what belongs where. A few key factors help guide that decision:
- Regulatory complexity and speed of change
- Depth of internal tax expertise
- Level of process standardization across entities
- Quality and availability of source data
- Maturity of your current technology stack
- Number of countries, states, and regimes in scope
A common pattern for large enterprises looks like this.
Retain in-house:
- Tax policy and governance
- Risk and materiality decisions
- Design of tax-sensitive processes in ERP and billing
- Dispute resolution strategy and handling high-stakes audits
- Communication with the board, auditors, and senior leadership
Co-source or outsource:
- VAT and sales tax return preparation and filing
- EPR registrations and periodic reporting
- Data extraction, transformation, and mapping
- Standard reconciliations and control checks
- Routine interactions with local authorities on everyday questions
Seasonality also matters. Many groups see pressure spikes around:
- Quarter ends and year-end close
- Calendar-year reporting deadlines
- New regulations going live mid-year
Co-sourcing lets you flex capacity across markets without constant hiring and training. The provider covers peaks on a shared platform, while your team stays focused on decisions and exceptions instead of firefighting every deadline.
Designing SLAs, KPIs, and Control Frameworks
A co-sourced model only works if expectations are clear. That starts with SLAs that match how your business runs. Key SLA elements usually include:
- Scope of services by country, tax type, and entity
- Timelines, cut-off dates, and calendar alignment with your close
- Data handover rules, formats, and quality standards
- Escalation paths when issues or delays appear
- Regular performance review meetings and continuous improvement steps
From there, build a KPI set across four simple dimensions:
Timeliness
- On-time filing rate by country and tax type
- Response times to questions from your team or authorities
Accuracy
- Error rates and number of corrections filed
- Frequency and size of post-filing adjustments
Effectiveness
- Audit outcomes and frequency of queries
- Trend in penalties, interest, and notices
Efficiency
- Cycle time from data cut-off to signed filing
- Automation rate and reduction in manual touchpoints
- Cost per filing or per country in scope
Control and auditability sit on top of all this. For large enterprises, that often means:
- End-to-end process documentation that matches your policy framework
- Standardized workflows with clear maker-checker segregation
- Digitally logged approvals for key steps and tax positions
- Evidence trails that show how each number in a return was built
- Integration with SOX and internal audit testing, including access controls
A SaaS-based approach helps by keeping workflows, documentation, and data in one place. Real-time dashboards give finance, tax, and audit teams a shared view instead of trading email and offline files.
Governance, Risk Management, and Transition Planning
Good design still fails without good governance. For co-sourcing, that means a clear model for who does what, who decides what, and how often you meet. Typical elements include:
- Defined roles across tax, finance, IT, and the provider
- A steering committee that meets on a regular schedule
- Decision rights for policy changes, new countries, or new channels
- A shared issue log and agreed process for change requests
Transition to a co-sourced model should be phased, not a big-bang shift. A simple path often looks like:
- Discovery and current-state assessment, including process and system maps
- Pilot group of jurisdictions or tax types to test the model
- Staged rollout by region or business unit, tied to your reporting calendar
- Parallel runs for at least one or two cycles before full cutover
You also need structured risk management, including:
- Business continuity and backup filing procedures
- Clear playbooks for system outages or local portal issues
- Regulatory change tracking with shared ownership between teams
- Ongoing vendor risk assessments, including security and performance
A RACI matrix helps keep dependency risk under control. Everyone knows who is responsible, who approves, who is consulted, and who must be informed at each step.
Turning Co-Sourcing Into a Strategic Advantage
When co-sourcing is designed well, indirect tax stops being a constant scramble and starts to support growth. Your team spends less time moving data between systems and more time on analytics, scenario planning, and helping the business enter new markets with confidence.
At Taxually, we focus on that blend: instant registrations, automated data processing, and global filings combined with expert support. For large enterprises, a model like this can make tax compliance outsourcing feel less like handing things away and more like building a scalable, resilient operating model that keeps regulators, auditors, and leadership aligned.
Streamline Your Global Tax Compliance With Expert Support
If you are ready to reduce risk, save internal resources, and improve accuracy, our tax compliance outsourcing solution can help you get there faster. At Taxually, we combine advanced technology with specialist expertise to manage complex, multi-country tax obligations for you. Tell us about your current challenges and we will design a tailored approach that fits your systems and workflows. To discuss your needs directly with our team, simply contact us today.
Frequently asked questions
FAQs on Co-Sourced Tax Compliance Models
Q: How is co-sourcing different from traditional tax compliance outsourcing?
A: Co-sourcing blends internal and external teams in one model. Your tax team stays in charge of policy, risk, and key relationships, while the provider runs agreed processes on a shared platform. Traditional outsourcing often replaces most internal activity and can limit visibility and flexibility.
Q: What types of tax activities are least suitable for outsourcing?
A: High-judgment, business-specific work, like designing tax policy, managing sensitive audits, or advising on complex structures, is usually best kept inside the company. These tasks depend on deep knowledge of your strategy and risk appetite.
Q: How do we keep auditability and control if a third party handles filings?
A: Ask for full data lineage, standard documentation, and access-controlled audit trails. Build workflows where internal tax signs off on key positions, and make sure controls line up with internal audit and SOX so accountability is clear to regulators and auditors.
Q: What internal capabilities do we still need with a co-sourced model?
A: You still need a strong core tax team for governance, policy, vendor management, and oversight of KPIs and controls. People who understand tax-sensitive processes in ERP and billing, and who can read and act on analytics, remain central.
Q: How long does a large enterprise transition usually take?
A: Timelines vary by number of countries, systems, and tax types, but multi-country transitions often span several reporting cycles. Many large groups start with a pilot cluster, run parallel filings for a short period, then expand in waves that match financial year-ends and major regulatory dates.
