Thank you for your query.
The Immigration rules, called Appendix FM, states clearly that you must have an income of £18,600 gross.
The Immigration rules also state that if you have £65.000 cash savings, then you can rely on this.
In your case, you earn £15,300 and so have a shortfall. If you have savings, you can combine that with your income. There is calculation for this, and I draw your attention to pages 46 and 47 of the following guidance: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/525708/Appendix_FM_1_7_Financial_Requirement.pdf
You other option is the Surinder Singh route and more information can be found here:
This route means that you have to live in a European country and work there. In this route, you do not need to meet the financial requirement of £18,600.
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