With less than six weeks to go until Christmas. it's time to get those all-important lists in.
But if you want to make sure it gets to Santa Claus in time, you need to pop it in the post no later than December 8 - which is just over three weeks away.
Royal Mail has been looking after Santa's mailbag for more than 50 years and ensuring his post gets delivered safely to the North Pole.
If you're planning to get your child's letter in the post soon, make sure you include their full name and address so Santa knows where any presents should be delivered to.
Each year, Santa's helpers at the Royal Mail help to deliver thousands of letters from children across the UK.
Alex McConnell, Royal Mail Chief Elf, who ensures children’s letters reach Reindeerland at the North Pole, said: “Royal Mail plays a special part at Christmas.
"We are proud that for over 50 years, Santa has allowed us to help manage the hundreds of thousands of special letters he receives from boys and girls across the country.
“His special team of elves at Royal Mail enjoy taking a peek at what children are asking for and helping Santa reply to these special letters.
"Remember to include your full name and address on your letter so Santa can reply to you!”
To ensure Santa receives your letter on time, please make sure you write to him, using the correct address, on a stamped envelope.
Don't forget Santa needs to know your full name and address to reply.