Taking somebody to the Small Claims Court in the UK will cost you money, there is a sliding scale of costs depending on how much you claim, for example, if you are claiming £1000 from a person or business, it will cost you £140* in Court fees. If you are claiming for £4000, the fees will be £520*.
(*These are the total Court fees to take a Small Claims case, in England & Wales, through to a Judgment, figures correct as at Sept 2018).

There are two separate sliding scale court fees that make up the figure(s) quoted above, each fee is payable separately. You pay one fee up-front to start your claim and the other fee is payable as the Case progresses through the Court system, if you win the case you’ll get your fees back,
e.g. if you claim £4000 and win the Case, the defendant will be ordered to pay your claim + costs, i.e. £4520.

Small claims court fees are detailed in HM Courts Form EX50 (see below for the link and more on navigating EX50), they are as follows:

  • A Fee to Start your Claim (sliding scale: £35-£410)
  • A Hearing Fee (sliding scale: £25-£355) payable if/when your case goes to a Hearing.

HM Courts Form EX50 provides details of all small claims court costs. It's a large document and IMO a difficult one to navigate as it contains details of fees for all Courts (High Court, County Court, etc). To work out the costs applicable to your claim, search for the following terms in the EX50 document :

Starting your claim
Hearing Fees

Court costs are (only) payable by the Claimant, and are paid as the case moves through the court system; there are no equivalent court fees for the defendant to pay. Your court fees are automatically added to the amount of your Claim and will therefore be paid by the defendant, if you win the Case.

Additional Fees - Enforcing the Judgment.
There is a possibility that you may incur additional court costs even after the Judgment. If you win your case and the defendant refuses to pay, you can, and probably should Enforce the Judgment, which again requires a fee. As of Sep 2018, all the enforcement options (e.g. A Warrant of execution, to send in the Bailiffs) have a flat fee of £110.
As with the other Court fees, the enforcement fee is added to your Claim, and assuming the defendant does eventually pay up, you will get the fee back.

The Remissions System.
There are a number of Remissions or exemptions to court fees for those people on low pay or in receipt of Income Support, Job Seekers allowance or Working tax Credit etc. There are actually quite a wide range of remissions available so it's certainly worth checking to see if you qualify. See form EX160A for an explanation of the remissions system and to check your entitlement.

To Summarise; There are fees payable as your Case progresses through the Court system, the fees provide funding to the HM Courts Service, but also serve to discourage timewasting and frivolous claims. As a typical claimant, you'll probably pay around ~£300 in fees to have your day in Court, and considering that the defendant may owe you a considerable sum already, it's important to take an objective look at your Claim and make a hard-headed decision as to whether to go forward with your Court action (i.e. is it winnable?). If you are unsure, a consultation with a Legal advisor or Solicitor may be worthwhile.

MY CASE: I claimed £1650 from my Landlord who refused to return my deposit and 6 weeks advanced rent. The fees were £105 to start my Claim using www.moneyclaim.gov.uk, then a Hearing fee of £170. And finally, £110 to Enforce the judgment; Total £385. See My Court Case for details. I won the case and the fees were added to my Claim, i.e. the final cost to my Landlord was over £2000 (Note: Figures are correct as at Sep 2018).

For guidance on starting your Court Action see: Planning/Starting Court action with Money Claim Online