Starting or changing jobs

Providing the right information when you start a new job helps ensure your tax code is correct from the first pay day and avoids the risk of paying too much tax.

When starting a new job or taking on additional employment, your new employer will usually send your income details to HMRC, which are used to calculate your tax code. If this information is not provided in time, or you choose not to share it, you may be placed on a temporary emergency tax code.

To avoid this, you should provide your new employer with your P45. If you do not have a P45 or do not wish to supply it to your new employer then you should complete HMRC’s starter checklist.

You can check your employment details via HMRC’s online services or mobile app, ensuring only one employer is using the standard 1257L tax code and that your estimated income is accurate. This should be available to view within 6 weeks after your first pay day.

If your records are incorrect or incomplete, you can update your employer details, add or remove employers and amend your estimated income or benefit information directly with HMRC. These updates can help prevent underpayment or overpayment of tax.

These changes may or may not affect your tax code. If the changes result in a change, HMRC will notify your employer.

Source:HM Revenue & Customs | 05-01-2026
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Aitch
Aitch is the visionary founder and CEO of CIGMA Accounting Ltd, a boutique accounting and tax advisory firm with offices in Wimbledon and Farringdon, London. With over a decade of experience, Aitch has built a reputation for strategic tax planning, complex HMRC compliance resolution, and innovative AI-powered accounting workflows that help SMEs, landlords, and high-net-worth clients streamline their finances. His expertise spans corporation tax, inheritance tax planning, R&D tax credit claims, capital allowances, and international tax matters, making him a trusted advisor for clients seeking to minimise tax liabilities while staying fully compliant. Aitch is passionate about bridging traditional accounting principles with cutting-edge digital solutions, allowing businesses to operate efficiently and future-proof their financial systems. Through CIGMA, he aims to make accounting smarter, faster, and more human-centric - empowering clients to focus on growth while staying ahead of regulatory changes.