Vietnam’s most significant corporate income tax reform in decades took effect in late 2025. At its centre is a provision that few FDI companies have fully modelled: a 200% R&D super-deduction under Article 9(a1) of Decree 320/2025/ND-CP. For every qualifying dong spent on research and development, foreign-invested enterprises can deduct twice that amount from taxable income. A company spending VND 10 billion on qualifying R&D reduces its taxable income base by VND 20 billion. At the standard 20% CIT rate, that translates to VND 2 billion in additional tax savings, on top of the actual expense deduction.
The 2025-2026 CIT Legislative Framework
Three Laws Every FDI Company Must Know
Vietnam’s CIT framework was restructured across three instruments. Law No. 67/2025/QH15, enacted June 14, 2025 and effective October 1, 2025, replaced the entire previous CIT law. Decree 320/2025/ND-CP, effective December 15, 2025, provides implementing guidelines, including the R&D super-deduction under Article 9(a1). Circular 20/2026/TT-BTC, effective March 12, 2026, adds guidance on foreign contractor treatment and capital transfer rules. All three apply from the 2025 tax year.
Decree 20/2026/ND-CP, issued January 15, 2026, extends the 200% R&D deduction to startups and SMEs under Resolution 198/2025/QH15 on private sector development. The deduction is now available across the full spectrum of FDI company structures.
How the 200% R&D Super-Deduction Works
The Mechanics Under Article 9(a1) of Decree 320
The Vietnam R&D tax deduction operates as a double deduction on qualifying expenses. R&D costs incurred in the tax year are deductible at up to 200% of actual costs. This is a deduction against taxable income, not a tax credit against the CIT liability. The reduction flows through the income base on which the applicable CIT rate is applied.
The deduction is supplementary: the company first deducts the actual R&D expense (as it would any other allowable cost), then applies an additional equivalent deduction. The two combined produce the 200% total. Expenses already drawn from the Science and Technology Development Fund cannot also claim the supplementary deduction, the mechanisms are mutually exclusive for the same costs.
The Two Mandatory Conditions
Both conditions must be satisfied simultaneously in the same tax year.
Condition 1, Activity definition: R&D activities must be conducted and defined under the laws on science, technology and innovation. An internal company label of “R&D” is insufficient. The activity must fall within the statutory classifications.
Condition 2, No-loss position: After applying the supplementary deduction, the enterprise must not be in a loss position. The additional deduction cannot create or increase a taxable loss. This is the condition that most FDI companies fail to model before committing to an R&D programme.
What Qualifies as R&D: The Science and Technology Law Definition
Qualifying Activities Under Vietnam’s Science and Technology Framework
Fundamental research covers systematic study to generate new knowledge without a specific practical application in view. Applied research covers systematic study directed toward specific practical objectives, developing new materials, processes, or understanding. Experimental development covers systematic work drawing on existing knowledge to produce new materials, devices, products, or processes.
Routine activities do not qualify. Quality control testing, standard software updates, data collection as a primary activity, and minor product adaptations to existing designs fall outside the statutory definition. FDI companies that treat internal product testing as R&D without verifying activity classification against the science and technology law definitions are claiming a deduction that Vietnamese tax authorities will disallow on audit.
Sector-Specific Guidance
Qualifying R&D is clearest in semiconductor design and chip architecture, AI algorithm and model development, pharmaceutical compound and formulation research, industrial biotechnology process innovation, digital transformation activities producing technologies applied for the first time in Vietnam, and precision manufacturing process development.
Decree 320 also expanded CIT-exempt income to include income from innovation and digital transformation contracts, income from products created from technologies applied for the first time in Vietnam, and income from products generated during pilot production phases. This creates a combined tax incentive: the R&D expense deduction on the cost side and an income-side CIT exemption on the revenue side of the same project.
The No-Loss Condition: How to Manage It Across the Tax Year
The no-loss condition is the 200% Vietnam tax deduction’s most consequential constraint. The maximum supplementary deduction claimable in any tax year is bounded by the enterprise’s pre-deduction taxable profit.
A company with VND 5 billion in taxable income before applying the additional deduction can claim a maximum of VND 5 billion in supplementary R&D deduction, not the full additional 100% if actual R&D costs exceed that figure. The unclaimed supplementary amount cannot be carried forward to a subsequent year under the current rules.
S&T Fund vs 200% Deduction: Choosing the Optimal Strategy
How the Science and Technology Development Fund Works
Enterprises in Vietnam can contribute up to 20% of annual taxable income to a self-established Science and Technology Development Fund. Contributions are deductible in the year contributed, reducing the taxable income base dollar-for-dollar up to the 20% cap. The fund must be deployed for qualifying R&D and technology activities within 5 years, or the unused balance returns to taxable income with interest penalties.
The Critical Interaction Rule and the Strategic Trade-Off
Expenses already drawn from the S&T Fund cannot also claim the 200% super-deduction. The two mechanisms are mutually exclusive for the same cost items.
This creates a genuine tax planning decision that no competitor currently analyses. The S&T Fund provides a dollar-for-dollar deduction up to 20% of taxable income with no loss-position restriction, it reduces the income base before the no-loss constraint applies. The 200% Vietnam R&D tax deduction provides a double deduction on actual R&D costs but is subject to the no-loss condition and requires compliance with the science and technology law activity definition.
For companies with large R&D budgets relative to taxable income, the S&T Fund may be more reliable, it avoids the loss constraint entirely. For companies with comfortable profit positions and tightly classified qualifying activities, the 200% deduction typically delivers greater total tax savings. The optimal strategy depends on the specific CIT rate applicable, the ratio of R&D spend to taxable income, and the stage of the CIT incentive period.
Stacking the R&D Deduction with CIT Holidays
How High-Tech FDI Projects Interact with the Super-Deduction
High-tech FDI projects qualifying under Law 67’s CIT incentive framework receive a preferential 10% CIT rate for up to 15 years, followed by 4 years of full CIT exemption, then 9 years at 50% reduction. Special investment incentive projects receive extended periods.
One significant change under Law 67 requires attention: location in an industrial zone alone no longer qualifies for CIT incentives. Projects must now satisfy sector criteria, high-tech, digital, green manufacturing, or geographic criteria such as SEZs or areas with extremely difficult socio-economic conditions. Companies relying solely on industrial zone location for CIT incentive eligibility under the previous law must reassess their incentive base from October 1, 2025.
Decree 20/2026: R&D Deduction for Startups and SMEs
Decree 20/2026/ND-CP extends the 200% R&D deduction to newly established SMEs and startups under Resolution 198. These enterprises already benefit from 3 years of CIT exemption from first ERC issuance. Decree 20 adds the 200% deduction on qualifying R&D costs during this same period, though the no-loss condition still applies.
The combined incentive stack is significant: zero CIT liability for 3 years plus double deduction on qualifying R&D expenditure. However, exclusions apply. Enterprises formed via mergers, divisions, or separations from existing entities do not qualify for the SME exemption. Legal Representatives with equity involvement in previously dissolved enterprises within 12 months also face restrictions.
Audit Documentation: What Tax Authorities Will Review
Building a Defensible R&D Claim
Vietnamese tax authorities assess R&D deduction claims on three dimensions.
Activity classification: Does the research activity meet the science and technology law definition? Internal project descriptions that do not map to the statutory categories will not withstand scrutiny. Registration or notification with the Ministry of Science and Technology or a relevant technology council, where applicable, provides institutional validation.
Expense substantiation: Payroll records for R&D staff, equipment purchase invoices, laboratory costs, third-party contractor agreements, and materials costs must be maintained. R&D expenses must be clearly segregated from general operating costs in the accounting system. Commingled expenses are the primary audit failure point.
S&T Fund separation: If some R&D costs were drawn from the S&T Fund in the same year, the supplementary deduction calculation must clearly exclude those amounts. The accounting separation between S&T Fund draws and direct R&D expense deductions must be documentable at the line-item level. Ministry of Finance standard forms issued under Decree 320 should be used throughout the documentation process.
How Viettonkin Supports FDI Companies with CIT Optimisation
For FDI tax directors and finance teams navigating Vietnam’s CIT reform, practical advisory expertise reduces both compliance risk and missed incentive opportunity. Viettonkin’s Vietnam tax and compliance services cover R&D expense qualification assessment, S&T Fund versus 200% deduction modelling, CIT holiday interaction planning, quarterly provisional CIT payment management, and annual CIT finalisation coordination.
Frequently Asked Questions
What Is the 200% R&D Deduction in Vietnam?
Under Article 9(a1) of Decree 320/2025/ND-CP, qualifying R&D expenses are deductible at up to 200% of actual costs when calculating corporate income tax. The enterprise deducts the actual expense plus an additional equivalent amount, subject to two conditions: R&D activities must qualify under the science and technology law, and the deduction must not create or increase a taxable loss.
What R&D Expenses Qualify for the Vietnam Super-Deduction?
R&D expenses qualify when the underlying activity meets the definitions in Vietnam’s Law on Science and Technology, covering fundamental research, applied research, and experimental development. Routine quality control, standard software updates, and minor product adaptations do not qualify. Expenses already drawn from the S&T Development Fund are excluded from the supplementary deduction.
Which Decree Introduced the 200% R&D Deduction in Vietnam?
Decree No. 320/2025/ND-CP, effective December 15, 2025, introduced the R&D super-deduction under Article 9(a1). Decree 20/2026/ND-CP, effective January 15, 2026, extended the deduction to startups and SMEs under Resolution 198. Both apply from the 2025 tax year.
