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An introduction to the tax system for the self employed

Rus­sell & Rus­sell can advise self employed peo­ple in the Lanark­shire area on all aspects of tax – here is an overview of some of the main things to con­sid­er.

Registering with HM Revenue & Customs (HMRC)

If you start work­ing for your­self, you must reg­is­ter with HMRC by 5 Octo­ber fol­low­ing the end of the tax year in which your self employ­ment starts, oth­er­wise you may be liable to a penal­ty based on the tax due to HMRC.

There are three ways that you can reg­is­ter:

Once you become self-employed, the tax rules are quite dif­fer­ent from those that may have applied when you were an employ­ee. Instead of tax (and nation­al insur­ance) being deduct­ed from your earn­ings at source, you must be pre­pared to receive a bill at some time in the future. This can be a nasty shock if you haven’t put enough mon­ey aside.

We aim to give you as much warn­ing as pos­si­ble of the like­ly tim­ing and amount of tax pay­ments, but it is not easy to do this dur­ing the first year of your new busi­ness, or if you do not keep your records up to date.

What profits do HMRC tax?

The start­ing point for the cal­cu­la­tion of tax­able prof­its is your prof­it and loss account. In cal­cu­lat­ing tax­able prof­its you are enti­tled to claim deduc­tions from your busi­ness income in respect of any expens­es incurred for the pur­pos­es of trade (with a few minor excep­tions).

For most of the equip­ment you buy for your busi­ness, you will be enti­tled to deduct the full cost (up to £1 mil­lion). For most cars, you can deduct only a pro­por­tion of the cost for each year you own them and use them in the busi­ness.

If you take stock out of the busi­ness for your own use, this should be shown as a sale at mar­ket val­ue in the accounts, and not at orig­i­nal cost. It may be bet­ter to show the orig­i­nal pur­chase as pri­vate expen­di­ture (draw­ings).

Tax is payable on the whole of the prof­its of a trade, and so pay­ments for your own ‘wages’ (draw­ings) are not deductible. How­ev­er, if your spouse works in the busi­ness, their wages are an allow­able deduc­tion, pro­vid­ed they are actu­al­ly paid and rep­re­sent a rea­son­able reward for what is done.

There are oth­er adjust­ments to prof­it for tax pur­pos­es which we can dis­cuss with you in more detail. There is also the oppor­tu­ni­ty to claim cer­tain flat rate deduc­tions; for exam­ple, if you oper­ate your busi­ness out of your home.

How does HMRC allocate profit to tax years?

From 2025/26, tax will be charged on the prof­its actu­al­ly aris­ing in the tax year so from 6 April 2025 to 5 April 2026. This will mean that if your busi­ness has an account­ing date oth­er than a date falling between 31 March and 5 April, the prof­its from two sets of accounts will need to be appor­tioned to cal­cu­late the prof­its relat­ing to the tax year. If the accounts have not been finalised pro­vi­sion­al fig­ures may be used.

How is the tax collected?

Tax returns

Assum­ing the busi­ness starts to trade in 2025/26, tax returns cov­er­ing income for the year end­ing 5 April 2026 will have to be sub­mit­ted to HMRC by the ‘fil­ing date’ which is 31 Octo­ber 2026 for paper returns and 31 Jan­u­ary 2027 for online returns. The return will include a self assess­ment of your lia­bil­i­ty to income tax and cap­i­tal gains tax.

There are auto­mat­ic penal­ties for late fil­ing of tax returns.

Payment of tax

Pay­ments on account of income tax and Class 4 nation­al insur­ance con­tri­bu­tions (NICs) for 2025/26 will be due on 31 Jan­u­ary 2026 and 31 July 2026. These inter­im pay­ments will be based on one half of the total lia­bil­i­ty (less any tax deduct­ed at source) for 2024/25. You will have the right to reduce pay­ments on account if you believe the income tax for 2025/26 will be low­er.

The bal­ance of income tax for 2025/26 is due on 31 Jan­u­ary 2027 (along with the first pay­ment on account for 2026/27 and any cap­i­tal gains tax for 2025/26).

If the busi­ness only start­ed to trade in 2025/26 and amounts payable for 2024/25 under Self Assess­ment were either less than £1,000 or you paid more than 80% of your lia­bil­i­ty via deduc­tion at source (eg through PAYE on your salary) then you should not have to make pay­ment on account. In this case the due date for pay­ment for 2025/26 will be 31 Jan­u­ary 2027.

Inter­est and penal­ties will be levied for late pay­ment.

What about National Insurance?

Self-employed peo­ple with prof­its above £12,570 are no longer required to pay Class 2 NICs but con­tin­ue to receive access to con­trib­u­to­ry ben­e­fits, includ­ing the State Pen­sion.

Those with prof­its between £6,725 and £12,570 con­tin­ue to get access to con­trib­u­to­ry ben­e­fits, includ­ing the State Pen­sion, through a Nation­al Insur­ance cred­it with­out pay­ing NICs.

Those with prof­its under £6,725 and oth­ers who pay Class 2 NICs vol­un­tar­i­ly to get access to con­trib­u­to­ry ben­e­fits includ­ing the State Pen­sion, will con­tin­ue to be able to do so at a rate of £3.50 per week.

Prof­its between £12,570 and £50,270 are sub­ject to Class 4 NICs at a rate of 6%. Any excess of prof­it above £50,270 is sub­ject to Class 4 NICs at the rate of 2%, with­out any upper lim­it. Class 4 NICs are col­lect­ed by HMRC and are payable at the same time as the instal­ments of income tax.

Save for your tax

It is essen­tial that you make prop­er pro­vi­sion to ensure the avail­abil­i­ty of funds to pay income tax and Class 4 nation­al insur­ance. Inter­est on unpaid tax is charge­able by HMRC, and is not deductible from busi­ness prof­its.

Cash basis for businesses

In order to try to sim­pli­fy the cal­cu­la­tion of tax­able income for small busi­ness­es, HMRC pre­vi­ous­ly had intro­duced an option­al alter­na­tive sys­tem for eli­gi­ble unin­cor­po­rat­ed busi­ness­es. Such busi­ness­es may cal­cu­late tax­able income fig­ures on a sim­pler cash basis if this suits the busi­ness. They will not have to com­pile fig­ures of debtors, cred­i­tors and stock, or dis­tin­guish between ‘cap­i­tal’ and ‘rev­enue’ expen­di­ture and will not have to com­pute cap­i­tal allowances to arrive at tax­able income.

Cash basis is the default posi­tion from 2024/25 onwards with an alter­na­tive to opt for the accru­als basis.

If you are self-employed in the Lanark­shire area and would like advice on tax or any oth­er busi­ness issue, con­tact Rus­sell & Rus­sell.