Can I claim back VAT on things I bought before I registered?

Yes, in many cases you can reclaim VAT on goods bought up to 4 years before registration, provided you still have them or they were used to make VATable supplies, and on services bought up to 6 months before registration. You'll need valid VAT invoices or receipts to support the claim, and the goods must still be on hand (not sold or used up) at the point of registration. This is a useful but sometimes overlooked reclaim, so flag it to your accountant when preparing your first VAT return.