You can give any amount of money or assets to your spouse or civil partner free of inheritance tax, providing they are UK domiciled or deemed domiciled.
Gifts out of normal expenditure
This seems like something that the average wealthier person could achieve gifting money regularly to children or grandchildren. However be aware HMRC will actually be keen to investigate the full details of your income and expenditure after your demise and your executors or administrators may well have to detail this on form IHT403. They would be looking to see a genuine surplus of income. If you have that surplus, fine, it should work well.
Each person is allowed to make an IHT-free gift of up to £3,000 in any one tax year. So if you are married or partnered that is £3,000 for each of you totalling £6,000. If say you didn’t use this annual allowance in the last tax year you can go back ONE tax year and use that unused allowance. So once again for a couple that could total £12,000 in this tax year, say. You could then continue at the £6,000 level every year you are alive. Bear in mind this doesn’t have to be money, it could be in the form of an asset providing it is not worth more than £3,000. A written valuation of the asset at the time of the gift would be good evidence.
Gifts on marriage or civil partnership
If someone is getting married or entering into a civil partnership, you can give them a gift, Inheritance tax free. The allowances are as follows:
Wedding or civil ceremony gifts of up to £1,000 per person (£2,500 for a grandchild or great-grandchild, £5,000 for a child).
You can, of course, gift more, but then the excess is potentially chargeable.
Small gift exemption
This allowance is a bit quirky. You are allowed to make any number of small gifts of up to £250 in each tax year to anyone you like. But if you want it to be tax-free you can’t add this on top of say the annual exemption. Although it has never been tested, you could post a pre-paid gift card or Amazon gift cards or iTunes gift cards of say £249 in value to every person in your area and give away your entire estate. In reality this exemption is seldom used.