LP10 is a type of letter that is issued by HM Revenue and Customs (HMRC) in the United Kingdom to individuals who are late in filing their Self Assessment tax return. LP10 stands for "Late Penalty for Failure to Notify a Liability to Tax."

The LP10 letter is issued to individuals who have not filed their Self Assessment tax return by the deadline and have not told HMRC that they have a liability to pay tax. The letter is intended to remind individuals of their obligation to file a tax return and to pay any tax that is due.

The LP10 letter includes information about the deadline for filing the tax return, the amount of tax that is due, and the penalties that may be incurred for failing to file the tax return or pay the tax. It also includes details on how to file the tax return and how to pay the tax.

If you have received an LP10 letter, it is important to take action as soon as possible to avoid incurring additional penalties. If you are having difficulty filing your tax return or paying the tax that is due, you can contact HMRC for assistance.