HM Revenue & Customs (HMRC) is to demand hundreds of pounds in uncollected tax from more than 140,000 pensioners.
HMRC failed to take account of the state pension when it sent out tax codes to people who first drew their pension this year.
It made exactly the same mistake in the two previous tax years, and the government announced in January it would cancel those bills.
But HMRC has told Money Box that it has no power to write off the latest money it has failed to collect - £130 million - because the mistake was discovered in the year the tax was due.
Paul Lewis talks to Ian Liddell-Grainger, Conservative MP for Bridgwater and West Somerset and chairman of the All-Party Parliamentary Group on Taxation and John Whiting, tax policy director at the Chartered Institute of Taxation.
The Chancellor has delivered his second Budget which he insisted is to 'fuel growth.'
While George Osborne said he did not need to ask the public for more taxes and spending cuts, there are still plenty of eye-catching measures.
Plans include a further cut to corporation tax; a shared-equity scheme aimed at helping first-time buyers on to the property ladder; a single-tier state pension of £140 per week; a consultation on merging the national insurance system with that of the income tax system; and a further increase in the size of the personal tax allowance.
Anita Monteith from the Institute of Chartered Accountants in England & Wales; John Whiting, tax policy director at the Chartered Institute of Taxation and director of the Office for Tax Simplification; and Mervyn Kohler, Age UK's special advisor join the programme.
Unofficial Olympics ticket-selling warning
Money Box has discovered that unofficial websites are illegally selling tickets for next year's Olympic games at vastly inflated prices.
One listener has paid a Norway-based website £190 for athletics tickets that she could have got for £32, if she had gone to the official ticket website.
Money Box investigates.
Energy bills examined
This week the big six energy companies have again been strongly criticised by the energy regulator.
Ofgem has accused the companies of bamboozling customers with too many confusing tariffs, and of failing to drop prices quickly enough when wholesale prices fell.
Paul Lewis speaks to Richard Frost from Npower to hear how he responds to suggestions that most customers have disengaged from finding the best deals.
BBC Radio 4's Money Box is broadcast on Saturday at 1204 GMT and repeated on Sunday at 2102 GMT.