GIFTS

Money that you receive as a gift is not taxable income to you, and you do not need to report it on your income tax return.  Money that you gave as a gift to someone else is not deductible for your taxes.

Turbo Tax does not support the gift tax form 709, but here is a link:

https://www.irs.gov/pub/irs-pdf/f709.pdf

https://turbotax.intuit.com/tax-tips/estates/the-gift-tax-made-simple/L5tGWVC8N

https://www.forbes.com/sites/ashleaebeling/2017/10/19/irs-announces-2018-estate-and-gift-tax-limits-...

If the share of the property that your sister gives you is worth more than $15,000 she will have to file a gift tax return, Form 709. She will not have to pay any gift tax unless the total of all gifts she has given in her lifetime is more than $11.7 million, but she has to file the return.

For 2021, the lifetime gift tax exemption is $11.7 million. This means that a person can give up to $11.7 million in gifts over the course of their lifetime without ever having to pay gift tax on it. 

However, the IRS requires that gifts exceeding $15,000 in value must be reported to them on Form 709.  @xmasbaby0  gave you a link to that form.

"Gift Tax" is somewhat of a misnomer.  Even though a gift tax return may be required, very few people ever actually pay federal gift tax. The purpose of the gift tax return is usually only to document a reduction in the allowable estate tax exemption.
See https://turbotax.intuit.com/tax-tools/tax-tips/Tax-Planning-and-Checklists/The-Gift-Tax-Made-Simple/...