Your balancing payment for this year (2015/16) and if applicable, an instalment for next year (2016/17) are due by 31st January 2017, together with your tax return.
If you cannot pay your tax bill, you should call HM Revenue & Customs’ (HMRC) Business Payment Support Service (BPSS). HMRC will ask you questions about your income and expenditure, assets and what you're doing to get your affairs in order. If they think you genuinely cannot pay your tax they may grant you an extension to settle your taxes in or agree a payment plan.
However, HMRC will not reduce the amount outstanding and they will still charge you interest.
If you don't think you can afford to pay your tax bill, you should do the BPSS as quickly as possible, as they tend not to look so favourably on taxpayers who have already missed the deadline. If they do grant you an extension, you will be expected to set up a direct debit. You must keep these payments up to date and pay your other tax. If you don’t, HMRC will normally cancel the arrangement and take legal action against you straight away.
If you don’t feel confident in negotiating with HMRC, feel free to contact your local TaxAssist Accountant who would be happy to liaise with HMRC on your behalf.