Understanding the cost structure while applying for a patent can help in making some important decisions. Hence, instead of having a generic idea about the overall cost, it helps if you are aware of the breakdown of the cost structure and the time of incurring such expenses.The substantial costs involved in processing a patent application includes, the fee that has to be paid to the patent office (statutory fee) and the fee paid to the patent service provider (professional fee). The professional fee varies based on the service provider you may select. Hence, in this article I will deal only with the statutory fee.The statutory fee depends on who the applicant of the patent is. The Indian Patent Office (IPO) has categorized the applicants into 2 categories:1. Natural person2. Other than natural personAny individual applying for a patent is considered as a natural person. On the other hand, all other entities that do not fall under the first category naturally fall under the second category. For example, legal entities, such as, companies would fall under the second category. It shall be noted that, a patent application can have more than one applicant, and even if one of the applicants do not fall under the first category, then the patent application is considered to be filed by the second category applicants.The patent office collects 4 times the fee from the second category applicants as compared to first category applicants.In this article, I will list down the fee applicable to the first category applicants. You may multiply this fee with 4 to determine the fee applicable to the second category applicants.Serial number 1An application for grant of patent has to be submitted. A fee of Indian rupee (INR) 1000 has to be paid while submitting the patent application in the Indian Patent Office (IPO). This is a mandatory fee. The exchange rate for 1 US dollars was Indian rupee 45 at the time of writing this article.Serial number 2An early publication request has to be submitted if one wishes to have their patent application published earlier than the patent office norm of publishing patent applications 18 months from the priority date (date on which you first file a patent application for your invention). This request carries a fee of Indian rupee 2500. The advantages of early publication include expedition of the patent application examination process.This is an optional step.Serial number 3A request for examination of patent application has to be submitted. A fee of INR 2500 has to be paid, requesting the IPO to examine your patent application. This fee can be paid within 48 months from the priority date. However, note that the patent office considers your application for examination only after receiving this fee. Hence, if you want to expedite the patent process, it is advisable to pay this fee at the earliest. This is a mandatory fee.Serial number 4The IPO accepts patent specifications, which has up to 30 sheets without charging any extra fee. However, if the specification crosses 30 sheets, a fee of INR 100/sheet for each extra sheet has to be paid to the IPO. This is a mandatory fee.Serial number 5Further, the IPO accepts patent specifications, which has up to 10 claims (no limitation on independent claims) without charging any extra fee. However, if the specification has more than 10 claims, then a fee of INR 200/Claim for each extra claim has to be paid to the IPO. This is a mandatory fee.I hope you find this article useful in filing patent applications in the Indian Patent Office.