What can a director legitimately claim through the company?

The golden rule is that the cost must be incurred wholly and exclusively for the business — and it's claimed through the company, not duplicated anywhere else. For home working, you can claim either a fair share of actual costs (a reasonable proportion of heating, lighting and broadband for the room you use) or HMRC's flat-rate allowance, but not both. For your own car, the approved mileage rates are 45p a mile for the first 10,000 business miles and 25p after that — keep a mileage log, and remember commuting from home to your normal workplace doesn't count. A mobile phone is tax-free if the contract is in the company's name; if it's your personal contract, only the business-calls portion can be claimed. Subsistence — meals and accommodation on genuine business travel — is claimable with receipts. And one firm rule: never claim the same expense through both the company and your salary or personal tax return; duplicate claims are exactly what HMRC challenges.