Hundreds of thousands of taxpayers will have to pay for stamps to file their tax return or settle their tax bill from next month.

From October 1, HM Revenue & Customs (HMRC) will stop sending pre-paid envelopes with VAT, corporation tax, PAYE and Excise forms, as well as freepost envelopes sent to taxpayers to allow them to send a cheque to cover their self-assessment tax bill free of charge.

Revenue & Customs said the move would save £8 million and would encourage people to file online, which, it said, would be more environmentally friendly.

But experts criticised HMRC's efforts to boost online filing, which comes less than a year after the department lost the bank and employment details of 25 million people.

Roy Maugham, a tax partner with UHY Hacker Young, the accountant, said: “This is unfortunate timing as HMRC’s recent data loss scandal is still fresh in everyone’s mind. You would think that they would be a bit more sensitive to taxpayers’ concerns before they tried to railroad them all into filing online."

But HMRC said: "We take the security of customer information very seriously and our priority is to protect the data of all our customers. Filing online is safe, secure and reduces errors and discrepancies; many of which are picked up instantly."

It also said that it would not be withdrawing pre-paid envelopes from those claiming child benefit and tax credits.

Bob Rothenberg, of Blick Rothenberg, the accountant, said that older people would pay the penalty for the withdrawal of the freepost facility. "Those who are not computer literate will suffer the most from this move, people who and try and communicate with the Revenue via post will now have to pay more. And if there is an inquiry, the cost will continue to rise."

But he said that in some cases, it made sense for businesses to use online filing. "It can save work, especially small traders who have to make quarterly VAT payments."