After a couple of months, she called him and said: "Give me back my documents and I'll do it myself." She has managed her own tax affairs ever since.
Although not everyone is as unlucky with their accountant as Ms Anderson, there is no reason why, if you're self-employed and your business is uncomplicated, you need one at all.
And, contrary to what we've been led to believe, self-assessment is going to make it easier to fill out your tax return, not harder. "Some people get confused about whether they have to calculate their own tax themselves," says Lynn Simpson of the Inland Revenue. "Self-assessment is actually filling in the tax return - it doesn't mean filling in the calculation yourself."
What do you need to do if you're self-employed? The most important thing is to keep good records throughout the year. At a minimum, this means keeping a written record of all the income of your business, and another one of all its outgoings.
If, like Ms Anderson, you work at home, then this will include a proportion of the money spent on heating and lighting as well as money spent on the materials you need to do your job. You also need to keep back-up records of your income and expenditure, such as bank statements, paying-in slips, telephone bills, invoices and receipts.
These are all things you should be doing anyway, of course, whether you have an accountant or not. Many of us, however, are daunted by the prospect of working out what we can claim against tax, and suspect that accountants have privileged knowledge in this area. In reality, the rules about what you can and can't claim are fairly straightforward and freely available from the Inland Revenue.
There are two categories of spending you can set against tax revenue expenditure (the nominal costs of running your business) and capital expenditure (one-off outlays).
The rules for revenue expenditure state that what you claim has to be wholly for the purpose of the business. If you use your phone for personal calls as well as business calls, for example, then you can only claim back the proportion used for business calls. On items of capital expenditure, you can claim a "writing-down" allowance of 25 per cent. Each year, the allowance is calculated by deducting previous allowances. For example, if you buy a computer for your business which costs pounds 2,000, the first year you can claim pounds 500 against tax. The next year you claim 25 per cent of pounds 1,500 (pounds 375), and so on.
The return itself is not as frightening as it seems. According to Ms Simpson: "We've done so much research to make the finished return as user- friendly as possible that if people want to fill it in themselves, there's no reason why they shouldn't be able to." The form is colour-coded, and comes with an explanatory leaflet telling you how to fill it in.
An advantage over previous years is that all the information goes onto the form - you no longer need to send in a statement of accounts. If you are still baffled by it, then the Inland Revenue will help. You can either phone your local tax office or a special helpline number available at evenings and weekends. Helpsheets are also available for people in particular trades. If you are worried about calculating your own tax, then Ms Simpson has surprising news: "We would prefer to do it for you." If you want the Revenue to calculate your tax, send in your return (without gaps) by 30 September 1997. Those, like Mary Anderson, who plan to do their own calculations, have until 31 January 1998.
A lot of publicity has been given to the fact that the Revenue will be carrying out random checks on people who have sent in tax returns. So is there any truth in the popular perception that you are more likely to be investigated if you haven't used an accountant. Her answer was short: "No"
Helpline numbers: 0645 000404 to order helpsheets or supplementary pages, seven days a week from 8am to 10pm; 0645 000444 for out-of-hours help in dealing with queries about your tax return, open from 5pm to 10pm, Monday to Friday, and from 8am to 10pm Saturday and Sunday.