Deciding on the right time to invest in the stock market can be tricky: we'd all like to buy at the lowest possible price but working out when that point has arrived can be a lot easier said than done! But investing on a regular, monthly basis may help you avoid that whole dilemma, and may smooth out the short-term ups and downs of the market in a process that is commonly referred to as 'pound-cost averaging'.

Selftrade's Regular Investment Service makes that easy, with access to a wide range of shares, investment trusts and ETFs in which you can invest monthly at the special low rate of £1.50 per purchase (sales are charged at the usual £12.50 per trade).

When you don't have lump sums available, or aren't sure about timing your investment purchases, investing regularly can help.

Averaging out the purchase cost of your investments over time helps smooth out the ups and downs of share prices. Click here for an example.

Available on all account types except CTFs (both Stakeholder and Self-Select), the Regular Investment Service enables you to invest from just £50.00 per month into a selected range of UK shares, ETFs and investment trusts. The investments you select will be purchased on the fourth Thursday of the month.

For monthly investment into funds check out our Fund Packages service too.

Setting up your regular investment is easy. Simply log in, choose the account into which you want the investments to go, and then click on 'Regular Investment'.

If you know the investment you want to make, enter its name or market code, or click on the Which shares can I trade? link to choose from the list of available investments. Then enter your monthly investment amount, minimum £50.00.

The latest time you can give us an instruction to be included in the current month is 22:00 on the fourth Wednesday of the month (i.e. the evening before the investment will take place). In setting up your regular investment instruction, you'll see the trade date on which it will become effective.

We'll then check your cash balance and, so long as you have enough available cash to make the full investment, we'll buy the investments you have chosen and add them to your account. Dealing will generally take place from 10:00 on that day.

Regular investment dates in 2008 >

If the number of whole shares you can buy each month doesn't take up your full monthly investment amount, the balance will be left as cash in your account and will not be rolled-up into the next month's investment. Click here for an example. Once your purchase has taken place, you'll have full details shown in your contract note, in the usual way.

You can set up more than one investment on each account type you hold with us, except CTFs where this service is not available. And you can change the amount you invest or your investment choice - but do make sure you do so ahead of the investment date: you can add, change or cancel your regular investment choice up until 22:00 on the fourth Wednesday of each month.

Changes affecting your investments: if the company you have chosen drops out of the FTSE 100 Index it may be removed from the available investment list and existing instructions cancelled. We'll let you know if this is to be the case so that you can make an alternative selection. However, if a share, Investment trust or ETF stops being listed on the London Stock Exchange your instruction will automatically cease and we'll tell you about it via a secure message.

The list of investments will also be reviewed from time to time and any changes affecting your existing choices will be advised to you by secure message.

Paying-in to your account: to make sure you have cash available for your investment, you can set up a monthly direct debit. To do so, simply complete the Direct Debit form and send it to us. Remember to allow time for us to set-up your initial instruction with your bank - this can take up to 10 working days - and allow 3 working days for each payment to reach your account ahead of the regular investment dealing cut-off time, 22:00 on the fourth Wednesday of each month.

You can also pay into your account using a debit card - log in to the account and choose the Payment tab. Debit card payments (up to a maximum of £20,000 per transaction) are available for dealing immediately.

However you choose to credit your account, do remember to ensure you've funds available in your account in time to meet the cut-off point: the earliest dealing date each month will therefore be the 22nd, so the earliest date funds would need to be in place is by the 21st. Please note that we will earmark cash to pay for your investment purchase on the evening of the fourth Wednesday of the month; so if you pay in before then do check you haven't used or withdrawn it ahead of it being earmarked for your regular investment order.

If you are arranging a regular credit into an ISA do bear in mind that the total amount you credit in any one tax year cannot exceed your ISA allowance. And for credits to your SIPP Dealing Account you will need to make arrangements via your SIPP Administrator, rather than crediting your account directly.

Terms and Conditions of the service: when you set up a regular investment instruction you'll be confirming your acceptance of the full Terms of service so please ensure you read and understand the Terms which are contained in section 2e, beforehand.

Investment purchases made using the Regular Investment Service will cost you just £1.50 per purchase. When the time comes to sell your investments, you'll pay our usual dealing fee, as shown on our Price List.

When investing in FTSE100 shares or investment trusts, you'll also pay stamp duty on your purchase. ETFs are exempt from stamp duty.