Yep, clothing is tax deductible. If it's used solely for the business (i.e. your workin' clothes - note that if you wore them for a boyfriend that would technically be personal use!) they are 100% tax deductible - your accountant / online tax advice places can advise more but basically in the long run in means that about 30% of the item's cost will come out of any tax that you have to pay.
Any small items - clothes, condoms, travel costs, you name it - that are in pursuit of the business (this also includes, for example, meals at a hotel while working or even travel to and accommodation at, say, a sex worker's convention or business advice weekend!) - these are ALL tax deductible.
Large items are classed as capital expenses and that works slightly differently - basically you can claim percentage of the total as tax deductible straight off, and then a diminishing percentage of the remainder of the value in following years - this is basically to account for depreciation.
Note that you can also claim on electricity, water, heating etc used during working time - you can calculate this accurately but typically HMRC will accept a negligible value without you needing to prove if - IIRC that's about ?20 per week. Don't forget to keep receipts for fuel (outcalls etc), car park tickets (not fines!) etc.
If an item is for personal AND business use then you'll need to state how much of the time it is used for business use, and then will be able to claim that percentage as tax deductible
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