HMRC does not rely only on the figures entered on a tax return. It can compare returns with information from employers, banks, letting agents, online platforms, overseas tax authorities and public sources. A difference does not automatically prove undeclared income, but it may lead HMRC to ask questions or open a compliance check.
During a tax investigation, HMRC rarely relies on one document alone. It may compare tax returns, bank transactions, business records, information from third parties, overseas financial data and publicly available material. Understanding how HMRC builds a picture can help taxpayers prepare an accurate response and explain apparent inconsistencies before HMRC draws the wrong conclusion.
