The deadline for the second payment on account for tax paid through self-assessment is 31 July 2016.
Payment is required if the tax bill is more than £1,000, unless you've already paid more than 80% of all tax you owe.
Two payments are due each year - on 31st January and 31st July. Each payment is half of the previous year's tax bill.
People who are already registered for self-assessment with HMRC can check their payments on account via your online account. This will show any payments on account already made and any payments owed.