Royal Mail issued the reminder online, by publishing a letter they 'received' from Father Christmas, urging kids to get their letters in the post by 6 December.
Each year, 800,000 letters are sent by children in the UK to Royal Mail's special address: "Santa/Father Christmas, Santa’s Grotto, Reindeerland XM4 5HQ".
They are then answered by Santa* himself (*postal workers and/or outside volunteers), but only if the letters are sent off in time.
"Christmas is a very exciting but busy time for me: the elves are making toys, the reindeer are practising their sleigh runs, and I'm busy preparing my list of who's been good this year.
"I need to let the elves know what to make so to help me out, please let me know what you would like as early as possible.
"I will be getting my sleigh ready for the long journey on Christmas Eve and in between I will try to reply to as many of you as possible. Please send your letters to me by Sunday 6 December so I have time to reply."
All children sending letters to Father Christmas must write the address carefully on a stamped envelope and include their full name and address so he can write back.
"We are proud that for over 50 years Santa has allowed us to help manage the thousands and thousands of special letters he receives from boys and girls across the UK.
"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."
Check out some brilliant letters to Santa for some inspiration in the slideshow below.
Lists/Letters for Santa
The Kid Who Knows How To Blow Off Steam(01 of15)
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(credit:Katie Odom)
The Kid Who Says What's On Her Mind, Literally, At That Second(02 of15)
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(credit:Catherine Naja)
The Kid Who Needs A Nicer Brother (03 of15)
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(credit:Emily Waldburger-Koszarek)
The Kid Who Has Read One Too Many Sci-Fi Books (04 of15)
This cute activity is a lot of fun since kids can also draw pictures for Santa. Get the printable: Pinterest (credit:Pinterest)
Dear Santa(02 of16)
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This festive template prompts kids to write what they'd really like for Christmas and draw a picture of it.Get the printable: Bird’s Party (credit:Bird’s Party)
For Little Ones(03 of16)
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Help young children practice their letters and writing skills with this cute sheet. Get the printable: Crystal & Co (credit:Crystal & Co)
Colouring Page(04 of16)
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Kids of all ages will get a kick out of colouring in their wish list after they write it. Get the printable: Kate Smith Designs (credit:Kate Smith Designs)
Fill In The Blank(05 of16)
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We love fill in the blanks, because they make wish lists so easy! Get the printable: Pinterest (credit:Pinterest)
Four Simple Things(06 of16)
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Help children fill this wish list out by asking them four simple questions. Get the printable: Education.com (credit:Education.com)
Frozen(07 of16)
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This is the perfect template for kids who are still obsessing over "Frozen."Get the printable: Hale Grafx (credit:Hale Grafx)
Draw & Explain(08 of16)
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This is a great activity to do either before writing a letter to Santa or to give to Santa as a letter. The sheet asks kids to draw what they want, explain what it is and why they want it.Get the printable: Step Into Second Grade (credit:Step Into Second Grade)
List It(09 of16)
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Lists make things easy. Have your child fill this one out on their own.Get the printable: Events to Celebrate (credit:Events to Celebrate)
Draw A Picture(10 of16)
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If your child prefers to draw rather than write, than this is the perfect letter template for them.Get the printable: It’s Overflowing (credit:It’s Overflowing)
Santa & Rudolph(11 of16)
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This cute template lets kids write a special message to Santa.Get the printable: Xmas Colouring Pages (credit:Xmas Colouring Pages)
Favourite Things(12 of16)
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This is a very practical list, because it asks kids to list some of their interests and favourite things, as well as what they want for Christmas. Parents can photocopy the list and give them out to relatives to help with their shopping. Get the printable: Pinterest (credit:Pinterest)
Santa’s Beard(13 of16)
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This simple wish list is quick and easy to fill out. Kids can even colour it in after filling it out. Get the printable: Free Fun Christmas (credit:Free Fun Christmas)
Long List(14 of16)
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This template will help older kids organise their wants this Christmas. Get the printable: The Chirping Moms (credit:The Chirping Moms)
Blank Colouring Page(15 of16)
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This blank letter template allows kids to get creative when writing their letter and colouring in the design.Get the printable: Melonheadz Illustrating (credit:Melonheadz Illustrating)
Naughty or Nice(16 of16)
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This template is great for older kids who don't want to waste time colouring and get right down to listing what they want for Christmas.Get the printable: Botanical Paperworks (credit:Botanical Paperworks )