I was actually the one who was considering making the offer. My house has sold, but I can't get the mortgage required for half of this bigger house until early next year as my accountant has done such a good job of making my business accounts look bad to lower my tax bill that at the moment the books are lolworthy (this is actually a good thing until someone other than the taxman is interested in how your business is doing). My year end is December, at which point the accountant can definately make my company look good enough to get the mortgage with THOSE books (which ironically will make me liable for a lot more tax .. but whadya' gonna do?).
Right, so you claim to be operating via a company, yes?
A company is required to pay tax 9 months after the year end, so if you are using a December year end then your most recent tax liability will have been for the year ended 31 December 2010, which would have been due on 1 October 2011. If that is the case, then your accountant will have to have filed your accounts by 30 September 2011, so the accounts should already be closed, unless they're going to be filed late and you're going to pay the Companies House penalty.
If you're talking about accounts for 2011, then those obviously won't be closed yet, but if that's the case then you won't have been required to pay any tax yet, as that won't be due until 1 October 2012, unless you are a large company and subject to quarterly instalment payments, but frankly I find that so laughably improbable that I'm not even going to entertain the notion any further, though I will note that paying artificially low quarterly instalment payments in an attempt to defer your payment is a criminal offence.
Or maybe you're actually self employed?
If that's the case, then you don't have a company, you have a sole trader business. Under self assessment, you pay your tax in two instalments - one by 31 January during the tax year in question and one by 31 July in the following tax year. There is then a top up payment on the following 31 January (along with the instalment for the next year) to make up any difference between what you've paid to date and what your tax return, which you'll be filing by that 31 January, shows. For a given fiscal year, your taxable profits are those for the accounting period ended within that fiscal year.
So, we're probably talking about the year ended 5 April 2011. Your taxable trading profits for the period would be those for the year ended 31 December 2010. You would have paid instalment payments on 31 January 2011 and 31 July 2011, each being half of your prior year tax liability, unless there was good reason to expect they'd be markedly lower than that, though again note that claiming they will be lower when you know they won't be is again a criminal offence. In any case, the instalments of tax that you are paying for the profits for the year ended 31 December 2010 bear no relation to the accounts for the year ended 31 December 2010 as they are based on your total tax charge for the year ended 5 April 2010, which is based on your accounts for the year ended 31 December 2009. Your accounts for the year ended 31 December 2010 don't need to be filed with HMRC until 31 January 2012, sure, but given that HMRC won't even be seeing your accounts until that point, there is zero benefit in your accountant cooking the books for you. In any case, any self assessment income tax that you will have been paying recently will bear no relation whatsoever to any accounts for the year ended 31 December 2011, which appear to be the ones that you are intending on being glowing so that you can get a stupendous mortgage.
In short, I think you're making this up as you go along. The alternative is that your accountant is taking you for a ride charging you for cooking the books to "keep your tax instalments low". I don't know which is more likely or more amusing.