When advising clients with online side hustles or e-commerce businesses, practitioners must recognise the enhanced data-gathering powers HMRC now deploys. Under section 349 of the Finance (No. 2) Act 2023, digital platforms like eBay must collect and report seller income data directly to HMRC.
These rules applied from 1 January 2024, with platforms submitting their first mandatory reports in January 2025. Consequently, HMRC systematically matches platform data against self-assessment returns to identify undeclared trading income and detect evasion.
Case law demonstrates HMRC’s historical readiness to use platform data to raise discovery assessments. In Vitalie Milasenco v The Commissioners for HMRC, the First-tier Tribunal upheld assessments built entirely on eBay seller feedback entries and PayPal transaction listings showing large deposits and shipping fee payments. The new reporting rules simply automate and expand this data-matching process.
The £1,000 Trading Allowance (ITTOIA 2005, s 783AD)
Your eBay tax calculator must first determine whether the client’s gross trading income exceeds the statutory trading allowance. Section 783AD of the Income Tax (Trading and Other Income) Act 2005 (ITTOIA 2005) provides an individual with a trading allowance of £1,000 per tax year.
“For the purposes of this Chapter, an individual’s trading allowance for a tax year is £1,000.”
- Full Relief: If the individual’s gross receipts from the relevant trade are £1,000 or less, full relief automatically applies, and the income is treated as nil for income tax purposes.
- Partial Relief: If gross income exceeds £1,000, the individual can elect for “partial relief” under section 783AK of ITTOIA 2005. Instead of calculating and deducting actual expenses, the taxpayer simply deducts the flat £1,000 allowance from their gross receipts to arrive at their taxable profit.
Crucially, the legislation prevents taxpayers from using the trading allowance to create or increase a trading loss.
Allowable Deductions: The Profit Method
If the client incurs expenses exceeding £1,000, the calculator should utilise the standard “profit method” by deducting actual allowable business expenses from gross receipts.
When evaluating an eBay seller’s expenses, tribunals acknowledge the reality of high platform and merchant costs. In Adspec Ltd & Anor v The Commissioners for HMRC, the tribunal noted that typical e-commerce trading incurs significant baseline costs, including seller premiums (10-15%), shipping costs (upwards of 15%), and merchant processing fees such as PayPal (approximately 3%).
2026/27 Tax Rates and Thresholds
To calculate the final liability, the calculator must apply the frozen 2026/27 tax rates and thresholds to the net taxable profit.
Table: Income Tax and NIC Rates (2026/27)
| Tax Band / Category | Threshold (2026/27) | Applicable Rate |
|---|---|---|
| Personal Allowance | Up to £12,570 | 0% |
| Basic Rate Income Tax | £12,571 to £50,270 | 20% |
| Higher Rate Income Tax | £50,271 to £125,140 | 40% |
| Class 4 NIC (Self-Employed) | £12,570 to £50,270 | 6% |
The Personal Allowance remains frozen at £12,570, and Class 4 National Insurance Contributions apply at 6% on profits between the Lower Profits Limit (£12,570) and the Upper Profits Limit (£50,270).
Making Tax Digital for ITSA Integration
For high-volume eBay sellers, the 2026/27 tax year triggers immediate compliance changes. Making Tax Digital for Income Tax Self Assessment (MTD for ITSA) becomes mandatory on 6 April 2026 for sole traders with a qualifying income over £50,000.
These clients must keep digital records of their e-commerce income and submit quarterly updates to HMRC using compatible software.
Table: MTD for ITSA Quarterly Deadlines (2026/27)
| Update Period | Submission Deadline |
|---|---|
| Quarter 1 (6 Apr – 5 Jul) | 7 August 2026 |
| Quarter 2 (6 Jul – 5 Oct) | 7 November 2026 |
| Quarter 3 (6 Oct – 5 Jan) | 7 February 2027 |
| Quarter 4 (6 Jan – 5 Apr) | 7 May 2027 |
The mandation threshold drops to £30,000 from April 2027, and subsequently to £20,000 from April 2028. Practitioners should ensure their calculator tools flag clients approaching these revenue thresholds for early MTD onboarding.
Next steps for research: Review the specific data exchange protocols established under the OECD Model Rules for Reporting by Platform Operators to understand precisely which transactional data points eBay transmits to HMRC. Additionally, examine how the Basis Period Reform transition profits from 2023/24 interact with a client’s MTD for ITSA quarterly reporting obligations in 2026/27.
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