Compliance
Compliance Essentials: Understanding Simple Assessment & Self Assessment Deadlines Under New Residence-Based Rules
As UK tax rules evolve with a residence-based system and the remittance basis ends, knowing when, what, and how to file under Self Assessment and Simple Assessment is more critical than ever.
By NomadicTax Research Team • 7 min read • August 31, 2026
## What are Simple Assessment and Self Assessment?
- **Self Assessment** is the UK’s standard method for individuals, self-employed persons, landlords, and others with non-PAYE income to report and pay their tax liabilities annually.
- **Simple Assessment (PA302 letter)** is used where HMRC automatically calculates your tax liability (for example, from employer, pension, or bank data) and notifies you without requiring the usual Self Assessment tax return. You still must pay any tax owed by the deadline, but you do not file a tax return unless HMRC asks. ([gov.uk](https://www.gov.uk/government/news/hmrc-urges-customers-not-to-ignore-simple-assessment-letters?utm_source=openai))
## Why the distinction matters under new foreign income rules
With the abolition of remittance and the rollout of the FIG regime, more UK residents have **worldwide income obligations**. These amounts may not always be visible to HMRC via employer or bank data, so Self Assessment remains vital for reporting foreign income and gains. Simple Assessment does **not** cover all kinds of income, especially if you:
- have overseas income,
- receive income from foreign entities, or
- need to claim reliefs or deductions outside standard data sources.
## Upcoming and current deadlines (Tax year 2025-26 / 2026-27)
- The tax year 2025-26 runs **6 April 2025 to 5 April 2026**. Self Assessment **online** filings are due by **31 January 2027**, and payment of any tax due is also by that date. Any **paper** returns are due earlier: **31 October 2026**. ([gov.uk](https://www.gov.uk/self-assessment-tax-returns/deadlines?source=post_page---------------------------&utm_source=openai))
- If you want HMRC to collect your tax (from your balance) through your tax code rather than paying in full, your return must be submitted by **11:59 pm on 30 December 2026**. Otherwise, you must pay by other means. ([gov.uk](https://www.gov.uk/self-assessment-tax-returns/deadlines?source=post_page---------------------------&utm_source=openai))
## What’s new in compliance under residence-based system
- From 6 April 2025, all UK residents must account for foreign income/gains under the FIG regime. Even if previously exempt via remittance or domicile status, you’ll now need to **report** worldwide income (or apply reliefs). OWR applies to qualifying work income, and FIG to foreign income/gains broadly. ([gov.uk](https://www.gov.uk/tax-foreign-income/non-domiciled-residents?utm_source=openai))
- For some people, **Simple Assessment** letters may be used for taxpayer obligations where data is available (employer, pension, bank sources). But foreign income or gains beyond those sources generally won’t be captured—so Self Assessment will still apply. HMRC is urging recipients not to ignore Simple Assessment letters. ([gov.uk](https://www.gov.uk/government/news/hmrc-urges-customers-not-to-ignore-simple-assessment-letters?utm_source=openai))
## Practical compliance tips
1. **Do a full income inventory each year**—combine all UK and foreign salaries, dividends, rental income, capital gains. If anything falls outside PAYE or other automatic data sources, anticipate Self Assessment duties.
2. **Check eligibility for Simple Assessment letters**, but don’t assume you’re covered if you have any overseas income or need to make FIG or OWR claims.
3. **File on time**: online returns (31 January), paper returns (31 October), payment deadlines (including payments on account, 31 July if applicable) must be met. Late filing or payment can trigger penalties.
4. **For digital nomads or returns to UK**: Elect OWR and/or FIG where eligible and include in Self Assessment returns—don’t wait for HMRC to catch up.
5. **Keep documentation**: days worked overseas vs UK; foreign income records; treaty statements; bank records—vital for both Self Assessment and potential HMRC checks.
## Common speed bumps and how to avoid penalties
- Missing the Simple Assessment deadline—leading to penalties even when no return is required.
- Failing to notify HMRC or file Self Assessment if you had income not captured through automatic sources (foreign employment, property abroad, etc.).
- Misunderstanding deadlines for payment on account (1st instalment, 2nd instalment, etc.).
## Summary
The shift to residence-based taxation in the UK places greater emphasis on accurate self-reporting of foreign income and on understanding the distinction between Simple and Self Assessment. Meeting deadlines, making required elections and claims, and maintaining good records are your best lines of defense. Under the UK’s current tax year (6 April 2025 to 5 April 2026), mark those important dates, and ensure you declare what HMRC expects—whether via return, relief claim, or both.