Unfortunately, anything of value that you receive from an employer for providing services must be treated as taxable income under IRS regulations. Employers can't give tax-free "gifts" except within the very narrow margin of certain defined employee benefit programs listed in publication 15-B. If they promised to pay $600 but actually paid $700, that's still all taxable income.
And you aren't being treated as an employee in any case. You are being treated as an independent contractor. This may be appropriate, depending on the circumstances, but it may also be improper. As a former church treasurer I get very annoyed at churches that skirt or ignore tax laws, because that's terrible stewardship and sends a bad message.
The difference between being an independent contractor and an employee depends on your work relationship and how much control each party has. The more control you have over your own work hours and duties, the more likely it is you are a contractor. The more control the church has over your working conditions, the more likely it is you are an employee. Employees must be paid minimum wage and receive other statutory benefits as required by state and federal laws.
If you agree with the classification as self-employed, then you need to file a self-employment tax return. This will create a schedule C listing your business income and any expenses, and the net business profit flows to your regular 1040 where it is combined with your other income, deductions and credits. In Turbotax online you must upgrade to the Self-Employer version, unless your total income is less than $39,000 in which case you can use the IRS-sponsored Turbotax FreeFile version. https://freefile.intuit.com
If you believe you should be classified as an employee, talk with the church first. If they don't voluntarily fix its you can file a form SS-8 to request the IRS to make a determination. However, the fines on the church if they are found to be in the wrong can be substantial, so I would not take this route unless you can't come to an agreement and you believe the church is abusing its position.
https://www.irs.gov/businesses/small-businesses-self-employed/independent-contractor-self-employed-o...
