Can I decline being promoted to Corporal?

Just came across this post, looks like you got your promotion to SGT, so congrats! Just know SGT Harrison this kind of mindset may prevent you from further growth in the military and definitely in the civilian world. Sometimes when you come across this opportunity or situation, just look at as an investment into yourself and those that you will lead in the future. In the military I recall being a PFC and doing the job of a SGT and SSG and in the civilian world this pattern only continues, but this sets you apart from those that just clock in and clock out. Is this bad, only if there is no positive outcome, but 9 times out of 10, this will only help you in the long run. Congrats again!

If you were looking at this and every opportunity with open eyes, denial is something you just don’t do. It’s a FREE learning opportunity and the opportunity to show everyone you are right for the job. As others have said, your focus is all about you…not your troops. Your troops should eat, sleep, get paid, do many before you…you should be their backbone.

The pay is the same for all E-4s

When I was a Private, I was witness to a section leader working to get a SPC promoted in order to be the NCO among us radio guys set to be in the TOC. This was one of the commo reps that was to maintain comms in the TOC. The SSG said one time: "The good thing about a Corporal is, when you need an NCO, you have an NCO. When you need a Joe, you have a Joe." It led me to call this position "NCJoe."
Unless the Army has drastically changed since I left in 2015, Team Leaders and Squad Leaders were often SPC's. You, likely would have been proud to be named one, unless (And this would be my guess, since the attitude probably would come through in either subtle or overt ways.) you're whole attitude projected that you weren't willing to take extra responsibility unless you were getting compensation for it.
Now, BLC was WLC when I was in. As a late-life entry and was older, I was often seen as a leader, even as an E-1 PVT. When I was promoted to SGT, I didn't have that under my belt, and it was supposed to be a requirement for promotion. It didn't even get mentioned as an issue until my acting 1SG find out I had never been and about half-heartedly threatened to pull my stripes. That was about six months before I was scheduled to get out on a med retire. It never happened.
You're refusing... it seems at least... to do the minimum in order to get the promotion and EARN the pay. "I DESERVE to get paid!" Why? Sounds like they're offering to put in a packet to send you to Ranger School. A leadership course. Hard work, but worth it if you can get through! Always represented by the tab once you've completed it. Maybe it's even something you WANT. But, you don't want to try until you get paid?
Turn down the 4187. It'll go into your file and likely will be used as a basis for a recommendation to deny or never offer you any promotions in the future.

In my career of 32 years I turned down a total of 12 promotions. I put the unit I wanted to stay in ahead of being promoted. I never cared about being a CSM and I certainly didn't need the money that promotions gave. I loved what I did and hated the idea of change and more than anything the idea of more responsibility. So don't let anyone tell you what you are ready for and what you are not. That is YOUR decision. Not your commands.

Take the rank and do the job. That's leadership. The money will come in time but your response is
what people and troops around you will remember. I held E3 and E4 in a E5 slot and the same as a E5 sitting in a E6 slot for 2 years. I just did the job.

a Classic response is,
"If You are offered a Promotion and you refuse it, then the odds of getting offered another promotion goes down, since they will believe you when you tell them you don't want to be promoted"

I was laterally promoted from Specialist to Corporal during my career. I personally think it is one of the most kick ass ranks in the Army. It showed me that my superiors acknowledged and had faith in my capabilities. I became a squad leader of a Vulcan ADA system ahead of some E-6's.

You can take my advice, or leave it. I was only on active duty for 5.5 years before breaking my neck and back in a line of duty injury, and was given a disability discharge during my second enlistment.

I've been in the civilian aerospace world since 1985, three years as a a technician, which was an hourly position and had compulsory union membership... and the last 36 years in a professional position, which is salaried and categorized as EXEMPT/Free Enterprise Personnel" (FEP) (NOT unionized).

All of the blowhards telling you that ALL civilian jobs pay for your new responsibilities were most likely hourly/union employees. Their union set very specific criteria for EVERY position, and you could only do what your job description said. Any increase in responsibilities would require a promotion/pay increase.

I also remember GIs complaining about how others would "sell their soul" or "stab you in the back" just to get a medal or commendation... WHAT THE FUCK DO THEY THINK HAPPENS IN THE CORPORATE WORLD, WHERE 'CURTAIN CLIMBERS' DO IT FOR $$$ AND MORE POWER. It is rarely the most qualified worker who becomes a manager... these promotions are usually given to the person who has no problems LYING to their subordinates and throwing them under the bus so it makes THEM look good!

While that sounds great, IT IS DECIEVING. Union pay grades frequently OVERLAP. If you get a promotion to a position with a much higher starting pay, you will get that new pay... but in most case, you will likely already within the range of your new pay grade, so you will get a 'token' pay increase.

For example, when I worked for Rockwell International on the B-1B Production Flight Test program, I was hired as a "Flight Operations Electrician" which was a Labor Grade (LG) 12. This was considered a 'journeyman' position. I applied for a promotion to a position as an "Aircraft Electronic Laboratory Technician", which was an LG-17, and the highest hourly scale in the company (and MUCH better working conditions)... because my pay as an LG-12 was already within the range of an LG-17, I was given a $0.10 per hour pay increase!

I later took a job as a customer training instructor with McDonnell Douglas. This was a "professional/engineering" position, so it was a salaried/Free Enterprise position. No union, no contract. Promotions and pay raises were based purely on your performance, not seniority. Same went for LAYOFFS. In a union position, you can be the best worker, but when layoffs come around, THEY WILL KEEP the most senior employee, even if they are totally worthless!

As a salaried employee, you were EXPECTED to put in a lot of extra effort and time... many times you were EXPECTED to 'take the lead' and do the job of a higher-level position. My pay increases as a salaried employee were ALWAYS much better than they were as a union/hourly employee, BUT I HAD TO WORK MY ASS OFF!

Additionally, after 14 years I had survived NUMEROUS layoffs, where much more senior employees were laid off.

ANYONE WHO TELLS YOU THAT THE CIVILIAN WORLD IS DIFFERENT FROM THE MILITARY IS FULL OF SHIT... As I pointed out to someone else, in most companies ONLY UNION POSITIONS pay you for every new responsibility, and that also comes with a price... Working conditions are usually MUCH less desirable, and job satisfaction is quite limited. I WOULD NEVER WORK AS AN HOURLY/UNION EMPLOYEE IF I CAN AVOID IT!

The only real difference between the military and the corporate world is that I am not subject to UCMJ and I can quit whenever I want!

Again, take my advice, or leave it... just keep in mind, for the past 43 years, I've I have worked on BOTH sides of the corporate world, for both good companies and bad companies... and in my job, I've worked extensively with everyone from new technicians, supervisors, and managers, to corporate executives, including directors, VPs and CEOs

Sure get all the extra responsibility and increased work load of being an NCO, but don't get compensated. Ha ha! And if you turn down the CPL or even merely suggest you don't want it, for good, logical, reasons, they'll treat you like a douche bag traitor. Rock and a hard place, my man.