HM Revenue & Customs (HMRC) has said it will be pursuing another 450,000 people over tax it has failed to collect.
These underpayment cases relate to the financial year 2007/08 and are in addition to the 1.4 million people who underpaid through the Pay as You Earn (PAYE) system in 2008/09 and 2009/10, which HMRC revealed in September.
The problems have been uncovered by a new computer system, installed at HMRC in 2009.
The government has also announced that any earlier tax it failed to gather through tax codes for years before 2007/08 will be written off - though any refunds due to people who have paid too much will be made back to 2004/05.
And 250,000 people who get the state pension, but whose tax was wrongly calculated in 2008/9 and 2009/10, will also be let off their tax bill.
The Law Commission has started a three-month public consultation about whether pre-nuptial agreements should be made legally binding.
We talk to family lawyer Jane Cowley from Howes Percival about what it should recommend, and how you can protect your financial affairs within a relationship as the law stands now.
And we talk to the Justice Minister, Jonathan Djanogly, about his ideas of insuring against divorce costs, and Tony Buss from legal protection providers, ARAG UK.
Hidden currency costs
Money Box has discovered that unsuspecting customers could be paying higher charges for currency conversion than they realise.
Some banks and businesses have started making up their own currency exchange rates, which can be significantly higher than the Visa and Mastercard spot rates.
Paul Lewis speaks to Bob Atkinson, from moneysupermarket.com.
The Pensions Bill 2011 started its progress through Parliament this week.
It implements the more rapid rise in state pension age (it will be at least 66 for anyone born on or after 6 April 1954), and it will introduce the new workplace pensions that start for some in October 2012, and will apply to everyone at work aged between 22 and pension age and who pays tax, from October 2016 - with full contributions due from October 2017.
People will be automatically enrolled in the pensions schemes - although it will be possible to opt out.
Tom McPhail, from Hargreaves Lansdowne, joins Paul to discuss the consequences of these planned changes, and the potential costs of waiting for the new workplace pensions to come into force.
BBC Radio 4's Money Box is broadcast on Saturday at 1204 GMT and repeated on Sunday at 2102 GMT.