Changing my rate of pay

My company offers the opportunity for any employee to participate in seasonal job opportunities. During orientation we were all told that the rate of pay for this second job would be TIME AND HALF of our regular rate of pay.  It was unclear as to if this only applied after you worked over 40 hours per week or was a flat OT rate.  I wasn't concerned because I always work 40 hours.

Recently I was reviewing my pay check stub and notice that my rate of pay for second job (at higher rate) was too high.  I had my immediate supervisor email the payroll department to clarify and determine if I was over paid.  I have an email confirmation that my rate of pay for the second job is a flat OT rate of my first rate of pay, BUT when I work over 40 hours at my first job then my second job is paid at OT the higher rate.  So the higher rate I thought was wrong is actually correct.  Also, I have been paid this amount on the last four checks and just didn't realize it. 

This explanation of my pay rate was not known by my supervisor for the second job.  When she found out she called the payroll dept.  Since I received the email confirmation about my pay I have worked 1 shift at my second job.  I just received my check for that shift and was not paid how the email explained.  When I called payroll back I was informed that my supervisor complained about how I was being paid because it threw off her budget.  So, they have another (legal) way to pay me and that's how they came up with the new rate.

I understand how they came up with the new rate (total hours worked / $ amount= average rate) but my issues is I was told I would be paid one way, worked a shift and then was paid for that shift at a lower rate.

Is this legal? What should I do?

Laymans suggestion:

If you make a major fuss you might get fired for some strange reason so think before you mouth off.

In general your employer can change your pay rate going forward but not for work already done. If you don't like the new pay formula you need not volunteer for extra work .

The employer must pay OT once past 40 hours or whatever your state law addresses which might be done daily .

But management can use a variety of steps to limit paying OT  such as

1. Set the rate for the second job at a lower rate and only pay OT based on lower rate  when your time passes 40 hrs

2. Only schedule folks with less than 40 hr on regualr job for the seasonal job  and then apply # 1

Paying  T +1/2  is not a very effective way to staff most jobs so I don't fault management for applying a more cost effective formula  ---but bottom line they must pay OT for hrs worked beyonf 40 or whatever --just they need not schedule people likely to trip into OP for this added work .

Its a bit of a 2 way street  --and not every seasonal job is easy to fill w/o willing workers who know what they are doing.

Whether management can mandate that you do extra work at a lower pay scale is a bit beyond me....but they sure can mandate that you do extra work!

Just for clarification, TX is not one of the very few states which mandates daily overtime calculations.

Describe the "new" way --that may be important for future.

I'd leave 1 week in past alone.