Saving Tax by Investing What you need to know. Last updated: 27 October 2020 1. If you are just starting semi-pro or professional work, you must register with HMRC as being self-employed. Failure to do so can incur a penalty. 2. Be honest with the tax authorities. It pays in the long run. Do not think that you can fool HMRC, as a high percentage of Tax Inspectors are top class university graduates. 3. When you write a letter to the tax authorities, keep a copy for future reference. 4. Get receipts for everything that you pay out. The tax authorities is entitled to see a receipt for everything you claim for. 5. If you are in doubt about any expenses/allowances, claim them. Give the full details to the HMRC and let it decide — that is its job. 6. Do not ignore communications from the HMRC — it will not go away and can get quite nastily persistent. This will only lead to estimates of your income being made, which always ends up with you paying excessive tax. 7. Do not write nasty letters to the HMRC, even if a mistake has been made, as it will not get you anywhere. A polite letter will grant you a far more sympathetic level of consideration. 8. In spite of all you have heard about Tax Inspectors, most are very fair people. They are there to ensure that you pay the correct amount of tax — no more, no less. In case you wondered, they do not get paid commission! 9. It is well worth putting some money aside to cover your tax bills when they do arrive.