forms?

How is your business set up?  If it is self employment or a Single Member LLC that is NOT a S corp you file it on Schedule C in your personal tax return.  Expenses go on Schedule C .

Here is a blank Schedule C

http://www.irs.gov/pub/irs-pdf/f1040sc.pdf

And instructions http://www.irs.gov/pub/irs-pdf/i1040sc.pdf

Here is some IRS reading material……

IRS information on Self Employment

http://www.irs.gov/Businesses/Small-Businesses-&-Self-Employed/Self-Employed-Individuals-Tax-Center

Pulication 334, Tax Guide for Small Business

http://www.irs.gov/pub/irs-pdf/p334.pdf

Publication 535 Business Expenses

http://www.irs.gov/pub/irs-pdf/p535.pdf

To write-off business expenses on a sole proprietor LLC, those are reported on schedule C of your 1040 personal tax return.

https://turbotax.intuit.com/ 

For a partnership, you would use Form 1065.

For a S-corp, you would use Form 1120-S.

https://turbotax.intuit.com/small-business-taxes/ 

For a C-corp, you would use Form 1120.

https://turbotax.intuit.com/small-business-taxes/cd-download/