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This factsheet tells you about old Self Assessment penalty rules and when they apply.
Find out how to report support payments relating to self-isolation due to coronavirus (COVID-19), on your Self Assessment tax return.
Agent authorisation Self Assessment technical specifications for software developers.
Use this technical documentation for individual returns if you're a software developer working with the Self Assessment Online service.
Use this guidance for support if you're a software developer working with the Self Assessment Online service.
Partnership returns technical specifications for Self Assessment Online software developers.
An overview of announcements made by HM Revenue and Customs (HMRC) for Budget 2014.
Find out about the treatment of debts, loans and securities for Capital Gains Tax.
Returns technical specifications for Self Assessment Online software developers.
Trust and estate returns technical specifications for Self Assessment Online software developers.
Use this technical documentation for partnership returns if you’re a software developer working with the Self Assessment Online service
If you received Horizon Shortfall Scheme (HSS) compensation between 6 April 2022 and 5 April 2025 you can get support with your Self Assessment tax return.
Use this technical documentation for individual returns if you're a software developer working with the Self Assessment online service.
Get help if you’re a tax agent or adviser who has clients with capital allowances for plant and machinery to declare on Self Assessment and Company Tax returns.
Don’t include personal or financial information like your National Insurance number or credit card details.
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